A. General References
Excellent reference materials for Miata maintenance procedures are the Mazda Shop Manual and the Mazda Miata Enthusiast's Shop Manual. The official Mazda shop manual addresses all the factory recommended maintenance procedures, and probably represents the single best reference if only one can be obtained due to cost factors. However, the illustrations in the factory manual are marginal and usually limited to diagrams or line sketches, or may have minimal detail or little orientation to structures adjacent to those being referenced. In many cases, the shop manual explanations assume some degree of mechanical knowledge beyond the basics, refer to Mazda special service tools, or are directed toward a technician presumably having some amount of prior Mazda-approved training. On the other hand, the Enthusiast's manual contains many excellent (black and white) photographs, a discussion of alternative procedures or tools when indicated, some humor, as well as some topics not covered in the Mazda manual (e.g., rustproofing, a discussion of fastener types, data on non-U.S. specification Miatas). Collective net.wisdom suggests that both manuals are complementary, and that access to both can be extremely helpful.
See the section on books for details on how to find them.
B. Underbody Access and Jack Points
Lifting the car and obtaining proper access for maintenance or other procedures always should be performed safely. It is strongly suggested that one should use jack stands, ramps, and blocked wheels when indicated, and never work under any car that is supported solely by a hydraulic jack.
To lift each corner, use the OEM scissors jack at the prescribed jack points as noted in the owners' manual, and as indicated on the side rails by small indentations/depressions. The purchase of a small hydraulic jack should be considered, particularly if a reasonable amount of maintenance is planned, since this will save time over the use of the OEM jack. In some cases, a wooden block with a small groove may need to be fabricated to allow lifting at the corner jack points without bending the metal flange under the side rails, when a jack other than the OEM one is used. Since many larger hydraulic jacks will not fit under the nose of the Miata, one also should attempt to obtain a jack no taller than 5" when fully collapsed to ensure that there will be sufficient clearance. Some netters have reported finding such models at their local Sears store.
To lift both front wheels simultaneously, use the factory-recommended jack point at the center of the front lower (U-shaped) brace, directly in the front of the engine oil pan. The rear lift point is at the center of the differential. Lift each end and place jack stands at the corners (just inside the OEM scissor jack points). There are a number of small, rectangular depressions in the underbody sheet metal near each corner, closer to the centerline of the car. Although these appear to be lift or support points, they are not. Jacking or supporting at these areas will result in sheet metal deformation, and is not recommended.
Alternatively, a quick and dirty (and probably safe) way to obtain undercar access is to nail two 2" x 6" wooden boards together, and drive up onto them as mini-car ramps. This usually provides just enough space to allow one to crawl under the car for inspection and fluid changes.
C. Break-in period
Everyone seems to have a different idea of how to break in an engine. Miata.net recommends following Mazda's break-in recommendations. They engineered it. They have a pretty good idea of how it should be broken in.
See the Mazda Break-in recommendations. Make your own decision.
D. Factory-Recommended Maintenance Schedules
Mazda defines "Unique Driving Conditions" as 1) repeated short distance driving; 2) driving in dusty conditions; 3) driving with extended use of brakes; 4) driving in areas where road salt or other corrosive materials are used; 4) driving on rough and/or muddy roads; 5) extended periods of idling and/or low speed operation; and 6) driving for prolonged periods in cold temperatures and/or extremely humid conditions. Since it very well may be argued that most cars are operated under conditions consistent with Mazda's definition of Unique Driving Conditions, a more conservative maintenance schedule should be considered. Unless otherwise noted, the information below has been adapted from the Mazda service manual for such conditions (U.S. specification cars, manual transmission):
5 months/5,000 miles: Replace engine oil and filter; lubricate locks and hinges.
10 months/10,000 miles: Replace engine oil and filter; lubricate locks and hinges.
1 year: Inspect A/C refrigerant amount and compressor.
15 months/15,000 miles: Replace engine oil and filter; inspect (or clean/replace) air filter element; inspect brakes and pads; tighten bolts and nuts on chassis and body; lubricate locks and hinges.
20 months/20,000 miles: Replace engine oil and filter; lubricate locks and hinges.
2 years: Inspect A/C refrigerant amount and compressor.
25 months/25,000 miles: Replace engine oil and filter; lubricate locks and hinges.
30 months/30,000 miles: Replace engine oil and filter; inspect drive belts; replace air cleaner element; replace spark plugs; inspect idle speed adjustment; inspect fuel lines; inspect cooling system and replace coolant; inspect brake lines, hoses and connections; inspect brakes and pads; inspect steering operation and linkages; inspect front suspension ball joints; replace transmission oil; replace rear axle (differential) oil; tighten bolts and nuts on chassis and body; inspect exhaust system heat shield; lubricate locks and hinges.
35 months/35,000 miles: Replace engine oil and filter; lubricate locks and hinges.
3 years: Inspect A/C refrigerant amount and compressor.
40 months/40,000 miles: Replace engine oil and filter; lubricate locks and hinges.
45 months/45,000 miles: Replace engine oil and filter; inspect (or clean/replace) air filter element; inspect brakes and pads; tighten bolts and nuts on chassis and body; lubricate locks and hinges.
4 years: Inspect A/C refrigerant amount and compressor.
50 months/50,000 miles: Replace engine oil and filter; lubricate locks and hinges.
55 months/55,000 miles: Replace engine oil and filter; lubricate locks and hinges.
60 months/60,000 miles: Replace engine oil and filter; inspect drive belts; replace air cleaner element; replace timing belt; replace spark plugs; inspect idle speed adjustment; replace fuel filter; inspect fuel lines; inspect cooling system and replace coolant; inspect brake lines, hoses and connections; inspect brakes and pads; inspect steering operation and linkages; inspect front suspension ball joints; replace transmission oil; replace rear axle (differential) oil; tighten bolts and nuts on chassis and body; inspect exhaust system heat shield; lubricate locks and hinges; inspect A/C refrigerant amount and compressor.
More than 60 months/60,000 miles: repeat above cycle.
E. Drain Plugs, Washers, and Tightening Torque
Engine oil drain plug: 19 mm (17mm for '99 and later)
Tightening torque: 29-41 N-m; 22-30 ft-lbs.
Transmission oil filler plug: square plug
Tightening torque: 25-39 N-m; 18-29 ft-lbs
Transmission oil drain plug: 24 mm socket
Tightening torque: 39-59 N-m; 29-43 ft-lbs
Differential oil filler plug: 23 mm socket
Tightening torque: 39-54 N-m; 29-40 ft-lbs
Differential oil drain plug: 24 mm socket
Tightening torque: 39-54 N-m; 29-40 ft-lbs
Aluminum crush washers are used on the engine oil, transmission, and differential oil drain plugs. All crush washers are the same size (part number 9956-41-800) with the exception of the '99 and later engine oil washer (part number 9956-41-400). Although there has been some debate whether they should be reused, there have been reports of people reusing old washers without any incident. However, the consensus seems to be that the washers are designed to crush a bit when torquing the drain plugs, and old washers won't deform to the same extent as new ones. Since the washers cost $0.85 to $1.00 each from dealers, it's probably a good idea to change them.
Although running the car until fully warm (and, for oil changes, until the oil pressure has stabilized as well) maximizes the probability that any particulates will be suspended and removed during fluid drainage, hot fluids also increases the probability of burning one's fingers. Collective net.wisdom appears to believe that this is a small price to pay to obtain maximum possible benefit from fluid changes.
F. Engine Oil
See also: Oil Changes for Novices
Oil change interval, filters, synthetic vs. conventional oil, and aftermarket oil filter use has been discussed extensively on the net. In general, most discussions indicate that either a good quality conventional oil, or synthetic oils, should be used. Mazda recommends oil change intervals of 5 months/5,000 miles for U.S. specification cars operated under "Unique Driving Conditions." However, many Miata.netters have agreed that changing conventional oil at 3,000 (or 3,333) mile/3 month intervals is reasonable. There also is some debate whether the same interval should be used for synthetics, which are designed to last longer. However, if possible environmental and cost issues are ignored, one could argue that more frequent oil changes are 1) likely to decrease the extent of circulating contaminants; 2) should not be harmful; and 3) probably adds to one's piece of mind.
As noted elsewhere in Tips from the Garage, a change in engine oil type or weight may affect lifter noise. Although Mazda recommends 10w-30 oil for most conditions, some netters have significantly diminished or eliminated lifter noise by switching to synthetic oils, or by using a lighter (i.e., 5w-30) weight oil. The use of a lighter oil to eliminate lifter noise has been suggested by Mazda as an alternative to installing lifters with larger oil passages in affected Miatas.
Engine oil capacity is 3.4 quarts for the 1.6 liter engine; the oil filter uses an additional 0.2 quarts. Addition of 4 full quarts will probably overfill the sump. Add approximately 3.5 quarts, then slowly add additional oil according to the dipstick markings. However, the oil sump capacity appears to have increased to approximately 4 quarts for the 1.8 liter engines; check the owner's and shop manuals specific for your car's year and model to be certain.
The use of aftermarket filters has been discussed at length. Advantages to such filters include the availability of larger sizes (with increased filtering capacity), and lower cost. Disadvantages include lack of information regarding the presence of pressure check valves and the use of non-OEM equipment. The consensus of numerous discussions favored the use of the OEM filter, particularly since these are available in quantity from many aftermarket suppliers and dealers who advertise in the MCA magazine, and are relatively inexpensive $4.00 to $5.00 each).
The major challenge associated with engine oil replacement is most likely filter access. The Mazda filter wrench, probably the only filter removal tool that will fit reasonably well in the confined space, is available through Mazda dealers, and has been advertised in the $4-7 range in the Miata Club magazine. The filter can be accessed through either 1) the engine compartment at the right side of the block; 2) underneath the car; or 3) through the right front wheel well after turning the steering wheel to left full lock. The relative ease of these approaches will depend on one's hand size (larger hands tend to get burned on hot engines using the engine compartment approach) and arm length (easier to reach the filter through the wheel well with a long arm). Alternatively, those who rotate their tires at the same time as their 3 month/3,000 or 3,333 mile oil change will have better access with the wheel removed). See Wheels and Tires for more information.
Rick Fischer has suggested an alternative oil change procedure; his method is as follows:
There are better ways to skin a cat, in this case change the oil filter on a 1600, don't know what the 1800s are like.
Jack and place on stands.
Remove the under engine fairing/drip pan - 1/2 doz. screws, 2 minutes.
While oil is draining, remove the intake manifold support bracket bolts, two off, one upper and one lower and withdraw the bracket. VOILA! One very exposed oil filter. A universal joint in ones forearm is not required, nor is a wrench, special or otherwise, - unless an "Arnie" clone tightened the filter.
Remove and replace filter.
I guess this is where I must take a little exception to tightening a filter tightly by hand. Installing a filter as tight as one can by hand is a no no. It is a bad engineering practice. That is why they can be so difficult to get off. If installed correctly, "spin on" filters come off easily.
A "spin on"`filter is installed, after lubricating the seal, by just spinning it on until it stops then tightening a further 1/8 to 1/4 of turn until snug. Doing it this way obviates the need for a wrench for removal and avoids damage due to overtightening.
When the engine is restarted after adding the necessary oil, check for leaks. If it happens to leak and this would be very rare, just tighten by hand until the weep/leak stops.
This whole process takes less than thirty minutes, after the first time.
It is also handy for those people into Concours condition cars, all the grotty bits under the engine can be accessed, the pan can be cleaned and polished, and the manifold bracket comes up quite nicely after smoothing, buffing and polishing. This can take considerably longer than 30 mins.
Due to the filter's awkward location, some oil spillage will probably be encountered. Some Miata.netters have found that placement of a disposable diaper under the old canister absorbs most of the spills. For those without kids, or friends with kids ("Hey, can I borrow a diaper? Gotta change some oil...") wadded paper towels work nearly as well to clean any drips. Access to the top of the plastic shroud just below the radiator can be obtained towards the front of the car. Paper towels also can be maneuvered into this space to clean any spilled oil.
Here's an interesting method to prevent spillage provided by Ken Warren:
Oil filters tend to be filled with oil when you're changing the oil. (No duh!) To avoid spilling the 6-7 oz of oil in the filter down the side of the engine, put a paper cup or bowl on the front subframe directly under the end of the filter. Then take an ice pick and puncture the filter *twice*. First punch a hole as far down the end of the filter as you can, and drive the pick in fairly deep (biggish hole). Then punch a second hole up near the top of the filter. (If you picture the oil filter as a cup held sideways, open end against the engine, the bottom of the cup would be the end of the filter.) Presto, the oil drains out of the filter and into your receptacle! Now you can spin the filter off with no worry that you're going to be wiping oil off everything underneath.
For those with Miatas without ABS braking systems, aftermarket suppliers have marketed attachments that relocate the oil filter to a more convenient point in the engine compartment (as well as provide other advantages, such as the use of larger OEM filters).
G. Transmission Oil
Mazda recommends 75w-90 weight oil for the manual transmission, changed at 30,000 mile intervals. Drain the oil by removing the 24 mm plug - any metal contaminants bound to the magnetic insert on the drain plug should be removed as well, and contaminants should be removed from the filler plug threads. Add a new washer (same size as the oil drain plug washer) and plug, then replace the oil through the filler hole (square bolt at the left side of the transmission). Oil should be added to the level of the filler hole (i.e., until the new oil runs out of the fill hole). Filling can be accomplished under the car using a hand pump available at most auto supply stores. Alternatively, a flexible tube can be placed into the filler hole and directed upwards into the engine compartment, where new oil can be added from above. Although the stated capacity of the manual transmission sump is 2.1 quarts, there are numerous reports that only 1.8-1.9 quarts actually fit before the new oil is expressed through the filler hole.
Mazda recommends that "sealant" should be placed on the filler plug threads before replacing the plug. The general consensus appears to be that anti-seize compound or a small amount of moly grease should be used to decrease the likelihood of having the steel filler plug seizing in the aluminum transmission housing.
If notchy or difficult shifting is experienced, some Miata.netters have recommended the use of synthetic transmission oils, such as Amsoil and Redline MTL. Some users of Redline MTL ($7-8/quart) have experienced smoother shifting, particularly the 1-2 shift when the engine is cold. The effect appears to be more pronounced in colder climates. MTL is a 75w-80 GL-4 gear oil that apparently behaves like a 75w-85 oil when warm, according to the company. Recent net.discussions have indicated that some Amsoil users have reported similar benefits. Proponents have also comments that use of MTL provides a "buttery feel" when shifting, and compensates somewhat for aftermarket shift knobs that are shorter (and thus require additional shifting effort). However, not all users of either Amsoil or Redline have reported benefits. As a result, it appears that either, both, or none of these lubricants may or may not be helpful for improving cold weather shifting, depending on transmission use, and/or local weather conditions.
H. Differential Oil
Mazda recommends 75w-90 weight gear oil for the differential, changed at 30,000 mile intervals. Drain the oil by removing the lower (24 mm) plug, and remove any metal contaminants bound to the magnetic insert on the drain plug. Add a new washer (same size as the oil drain plug washer) and plug, then replace the oil through the opening filler (23 mm) plug. Oil should be added to the level of the filler hole (i.e, until the new oil runs out of the fill hole). Filling can be accomplished under the car using a hand pump available at most auto supply stores.
Although some users recommend synthetic gear oils, there is insufficient data to determine whether there are any practical advantages to the use of synthetic vs. conventional gear oils over the expected normal life of the Miata. However, if like many of us you want to keep your Miata forever, synthetic differential lubricants probably would not hurt...
I. Fuel Filter
There are two fuel filters on the Miata. There is a high-flow, low-efficiency pre-filter mounted in the fuel tank that should not need to be replaced under normal conditions. The "regular", or high-capacity filter is mounted underneath the car, on the right side, a few feet forward of the fuel tank, and covered by a black plastic shroud. To remove the plastic shroud, first clean as much dirt as possible from the screws. Although they look like conventional Phillips head fasteners, they are actually delicate plastic expansion fittings, similar in appearance and function to hollow wall anchors. In some cases, one will need to gently insert a flat head screwdriver under the anchor flange while (gently, with little axial force) unscrewing. As noted above, starting with a clean fastener helps considerably. A more thorough description of these (and other) fastener types in well presented in the Miata Enthusiast's manual.
The fuel filter canister should be visible after removal of the plastic shroud. The filter is bolted to the underbody using two 10 mm metal screws. To avoid fuel draining out of the line (and down one's arm), the fuel lines exiting and entering the filter should be clamped off before final removal. Alternatively, the Enthusiast's manual suggests that a golf tee inserted into the end of the lines is just the right size. In any case, expect to spill at least a little bit of fuel. The new filter is installed in a straightforward manner by reversing the above steps (although the plastic shroud fasteners sometimes can just be pushed in by hand).
J. Engine Coolant
Mazda recommends coolant replacement at 30,000 mile intervals. The Phillips-head drain plug can be located through an access hole in the plastic shroud just under the radiator. The factory manual recommends draining the fluid, then replacing (in most cases) with a 50:50 mix of antifreeze and water. The overflow reservoir can be unbolted, removed, drained, washed, and reinstalled as well. The engine should be run until warm (e.g., the thermostat opens), and additional coolant added to the radiator neck. Finally, the radiator cap should be replaced, and additional fluid added to the overflow reservoir to obtain a coolant level between the indicated low/high marks. The purchase of a single gallon of good-quality antifreeze base is sufficient, since the Miata's coolant capacity is just over 6 quarts.
For the truly obsessive, the cooling system can be flushed with water (e.g., with a garden hose) while the engine is operating and drain plug is open. Then stop the engine and flush further with a few gallons of distilled water (available at some auto supply houses, grocery stores, or free from some fellow Miata.netters at schools with research laboratories - try colleagues with ".edu" in their address). Allow the radiator to completely drain, replace the drain plug, and add the appropriate mix (typically 50:50) of antifreeze and distilled water to the radiator and overflow reservoir, as noted above.
Mazda recommends the following procedure to evaluate refrigerant charge: 1) Run the engine at fast idle; 2) operate the air conditioner at maximum cooling for a few minutes; 3) determine the amount of refrigerant as shown below, by observing the sight glass:
If bubbles are present in the sight glass, there is insufficient refrigerant, and the system should be evaluated and recharged.
If no bubbles are present in the sight glass, this indicates either the correct amount of refrigerant, or too much refrigerant. If, immediately after the air conditioner is turned off, the sight glass remains clear, then there is too much refrigerant. The proper amount of refrigerant is present if, when the air conditioner is turned off, the refrigerant foams, and then the sight glass becomes clear.
L. Brake Fluid
Hydraulic fluid gradually absorbs moisture over time, and this moisture is potentially damaging to various brake system components. However, Mazda recommends only that the brake lines, hoses and connections be "inspected" at 30,000 mile/30 month intervals; replacement of brake fluid is not mentioned in the shop manual for U.S specification cars. Serious autocrossers, as well as those Miata.netters who wish to obtain maximum brake performance, generally advocate at least yearly brake fluid replacement. The Miata Club of America has recommended brake fluid replacement at two year intervals.
The Mazda Shop Manual recommends the following fluid replacement procedure:
Remove the brake fluid form the reservoir with a suction pump.
Fill the reservoir with clean brake fluid.
Attach a vinyl tube to the bleeder screw and place the other end of the tube in a clear container.
Pump out the old brake fluid by loosening the bleeder screws one by one,
and pumping the brake pedal until only clean fluid is expelled.
Fill the reservoir to the specified level.
However, more complete descriptions of brake fluid replacement are found in the Miata Enthusiast's Manual, as well as in the Miata Club of America magazine (vol 6(2), p. 52-53, winter 1994):
To replace the brake fluid, the car should be lifted and supported on safety stands and the wheels removed, as noted above. Care should be taken to avoid spilling any brake fluid onto painted surfaces (it's an excellent solvent), and to clean any dirt from the master cylinder and from around the bleeder screws to avoid introducing dirt into the system. The old fluid should be removed from the reservoir using a suction pump (or turkey baster-like tool). Alternatively, one of the bleed screws can be opened (with a bleed tube or flexible hose over the ball of the bleed screw), and the free end of the tube directed into a jar into which sufficient fluid has been added to submerge the tube end (to avoid air being reintroduced into the system). The brake pedal is then pumped repeatedly until the level falls to the bottom of the reservoir. An 8 mm brake wrench is required (either the Mazda special service tool, or a box-end wrench with a small slot in the box to allow it to slip over the brake line). The bleed screw is typically well-tightened, and the use of an open Crescent-type wrench may strip the screw.
Fill the reservoir with new fluid (DOT 3 or 4 is recommended). Starting from the caliper furthest from the master cylinder (right rear) and working around the car to the nearest (left rear, right front, left front - for left hand drive cars), bleed each line in turn until fresh fluid emerges from the bleed tube. The reservoir will require re-filling during this process - usually after 10 or more pedal strokes.
To avoid any chance for air aspiration into the system, an assistant is needed to monitor the bleed valve at the caliper, closing the bleed valve before one lifts up on the brake pedal: Open valve; pump pedal down; close valve; lift pedal; repeat about 20 times. Alternatively, a vacuum pump can be used to draw the fluid out through the bleeder valves. Such a brake fluid pump is available through auto supply houses such as Pep Boys, or through some of the MCA magazine advertisers. Instead of using the brake pedal and master cylinder to push fluid through the system, the pump uses a hand held vacuum device that evacuates a small jar. The jar's lid is vented to a rubber hose that is placed on the bleeder valve. When the pump induces a vacuum in the jar, the vacuum causes brake fluid to flow out of the bleed valve if it is opened. Again, it is important to monitor and refill the brake fluid reservoir periodically during the bleed procedure to avoid introducing air into the system. If this occurs, the entire system will require rebleeding.
M. Clutch Fluid
As with brake fluid, the clutch hydraulic system (which also uses brake fluid) will gradually absorb moisture over time, leading to potential damage to various clutch system components. Although there are no specific Mazda recommendations for clutch fluid replacement , it appears reasonable to change the clutch fluid when the brake fluid is changed (i.e., every 1-2 years); see above.
The Mazda Shop Manual recommends the following fluid replacement procedure:
Draw the fluid from the reserve tank with a suction pump.
Remove the bleeder cap from the clutch release cylinder and attach a vinyl hose to the bleeder plug.
Place the other end of the vinyl hose in a container.
Slowly pump the clutch pedal several times.
With the clutch pedal depressed, loosen the bleeder screw with the special service tool to let the fluid escape. Close the bleeder screw with the tool.
Repeat steps 4 and 5 until only clean fluid is seen.
Tighten the bleeder screw (5.9-8.8 N-m/ 52-78 in-lbs).
Add fluid to the Max mark.
Check for correct clutch operation.
However, a more complete description of clutch fluid replacement is found in the Miata Enthusiast's Manual, from which the following description is paraphrased:
When replacing the clutch fluid, care should be taken to avoid spilling any brake fluid onto painted surfaces (it's an excellent solvent) and to clean any dirt from the master cylinder and from around the bleeder screw to avoid introducing dirt into the system. If necessary for access, the car should be lifted and supported on safety stands (so the car is level), as noted above. The old fluid should be removed from the reservoir using a suction pump (or turkey baster-like device).
An assistant can be used for keeping the fluid level in the reservoir appropriately topped up. Pour brake fluid into a clear container to a depth of approximately 2 inches. While under the car, fit the wrench on the bleed valve while pushing one end of a clear plastic drain tube onto the bleed valve head. Immerse the other end of the tube in the container with brake fluid (to avoid introducing air into the system). An 8 mm wrench is required (or the Mazda special service tool).
An assistant should pump the clutch pedal slowly 4-5 times, using a stroke that will take 2-3 seconds per pump. Let the pedal rise, then at the start of the stroke, open the bleed valve about half a turn, allowing fluid to escape from the valve. As the stroke is completed, close the bleed valve (pedal against the floor until the valve is tightened) and let the pedal return to normal height. Repeat the above cycle until the fluid emerging from the bleed tube is completely free of bubbles, and appears fresh. Close the bleed valve, remove the bleed tube, and fit the protective cover over the bleed valve. Then lower the car to the ground, top up the master cylinder to the Max mark, and replace the reservoir cover and cap. The Enthusiast's manual also suggests procuring 3 beers: one for yourself, and one for each of your assistants.
Locks can be periodically lubricated with powdered graphite of graphite spray (particularly important for the trunk lock; there have been some reports of the key fracturing in the lock). The condition of the key should be inspected as well, and replaced if any signs of stress are noted. Hinges can be lubricated with a small amount of white lithium grease or chassis lubricant. Finally, the glove compartment sunscreen bottle should be checked periodically, and refilled when indicated.