I've noticed a lot of questions on here about bringing the maintenance up to date on low mileage, older Miatas. Since I've recently bought a few plus read everything in the garage and the forum until my eyes have bled, thought I'd assemble what I've learned. As always, some will disagree, some will do more and some will say this whole post is a waste of bandwith. I’ve made all of this into a nice checklist to help me through the process and remind me what I’ve done and yet to do.
Engine:
Induction system cleaning - low mileage cars are more susceptible to gumming of the fuel injectors because of the tendency of gasoline to deteriorate into a varnish like material over time. You can choose to go the Seafoam route or run a couple of bottles of Chevron Techron Concentrate through two tanks of gas. I also remove the throttle body and carefully clean the butterfly with throttle body cleaner and a soft brush (never carb cleaner!). I also replace the TB gasket, it’s $3.00 at advance auto and cheap insurance against an air leak.
Plugs and plug wires. NGK wires and BKR5E-11 or BKR6E-11 plugs are the recommended replacements. Don't skip this step unless the plugs and wires were changed within the last two years.
Oil/filter - Bonding/bleeding time!
Air Filter - Make sure to look into the airbox to make sure critters have not made a home there or at the least, stored their midnight snacks. I pulled two cups of dog food out of a car once that was garage kept and driven weekly!
PCV Valve - easy to check, cheap to replace.
Cam Angle Sensor – Check to see if it is leaking onto the heater hoses or down the back of the engine. If it is, plan to replace both the O ring gasket and the valve cover gasket.
Timing belt – I’m sure there will be lots of disagreement with this statement. I’ve pulled a timing belt on a 95 (11 years old) with only 44K miles and the belt was fine. I know yours may not have nearly the recommended mileage and I know it’s somewhat sealed from exposure to the general elements but; time and heat are the enemy of rubber. Much is made of the non-interference nature of the Miata engine and so you won’t bend any valves if it breaks. However, you are still talking about a broken rubber belt being thrown around inside the belt area if it breaks at high rpm. It is possible for parts of that belt to get wedged into the various pulleys that live there, doing damage. It won’t be catastrophic but it will add cost. Nuff said.
Water pump – If you have made the decision to do the TB, then the water pump on an older car should be a given. This is especially true if you don’t know the history of cooling system maintenance. If the previous owner wasn’t diligent about flushing the cooling system, the WP suffers.
Fuel filter – They are good for up to 60K miles but on an older car with 30K or more, it’s worth replacing it.
Drive belts – If they are more than five years old, this is an absolute. Don’t be fooled by looking at them with a flashlight and thinking they are fine. At the very least, take one off, bend it backwards and look for cracks – guarantee they will be there. If you’re doing the TB/WP, then this is a no brainer. Even if you’re not, they are relatively inexpensive and can leave you stranded if they break.
Hoses – Again, they will probably look fine on the outside but try pinching them and see how soft the rubber has gotten. Every low mileage old Miata I’ve purchased had the original hoses because they never “look” bad.
Brakes:
Brakes and clutch hydraulic systems. Many low mileage older Miatas will still have the brake fluid put in at the factory – makes me want to cry. Brake fluid absorbs moisture over time and deposits that moisture in places you don’t want it. A brake and clutch fluid flush are easy and inexpensive. Obviously check for pad wear as well, any leaking calipers and take the time to remove, clean and lubricate the slider pins.
Should your pads need replacing, I recommend the Mazda complete kit as it contains new hardware. Your hardware is probably reusable but is also losing some of its spring tension because of time and heat.
Rotors – Running your finger over the surface will tell you much about the condition of the rotors – if the are grooved badly, plan on resurfacing them at best, replacing them at worst.
Tires/Alignment:
Five to six years is the limit on a tire as to breakdown of the rubber. They will ride like something out of the Flintstones and just about the time you need maximum traction, you’ll find out there isn’t much left because the compounds have dried out.
Alignment – The Miata suspension is so good that it will tolerate being out of tolerance by quite a bit because it will still handle better than 95% of the cars out there, just not like a Miata should. Get a good four wheel alignment from a shop you trust unless the PO had it done within the last eighteen months.
Shocks – If the car has over 40,000 miles, the shocks are shot. You won’t really know this until you put on new ones and realize the night and day difference. Bouncing the car as in the old days is not effective on a coil over design. If you want the stock ride and height, the KYB G-2 shock is a nice stock replacement and are available for less than $200.00 a set.
Bushings – The Miata is heavily dependent upon bushings for it’s ride quality and handling. They will get brittle over time and cause a feeling of looseness in the car. It is worth replacing them to restore the ride, just make a decision whether to go with stock or a different material that provides more resistance.
Body:
Pivot points – Take white, spray lithium grease and lube all the pivot points in the car – door hinges, hood pivots, throttle cable and anything else that moves.
Exterior detail – It is doubtful the previous owner did the kind of exterior care you will expect for yourself. Take the time to do it right (clay bar, polish, wax) with the materials of your choice.
Front quarter panel cleaning – Every NA Miata traps debris inside the lower part of the front fender and there is no way for it to escape. It will absorb moisture and will not dry out, causing rot from the inside to the outside. Neglect this and you will be buying new fenders in a few years. I use a parts retrieval tool, the kind with the crows foot that extends out when you push the other end, to get every last bit of stuff out (this should be an annual ritual BTW). If you are already getting some minor rust on the very bottom of the panels, you can wire brush it and then coat it with Eastwood rust encapsulator in black. The black is almost an exact match for the black protector covering used on most NAs and will stop or greatly inhibit the spread of the rust. This is NOT the proper fix for rust but is inexpensive and will extend the life of those areas for quite some time before you need to visit a real body shop.
Interior detail – If you have leather seats, buy some good conditioner – I like Leatherique. Mazda leather is not going to ever be glove soft but restoring some of the oils will slow down the cracking process. If you like to treat your interior vinyl, I like 303 as opposed to armor-all but it’s your car, chose whatever makes you happy. I also take out my seats (eight bolts total), and clean all the stuff that has found it’s way into every hidden crevice in the car. I then shampoo the carpet while theseats are out, let it dry thoroughly and reinstall the seats. Freshens up the smell of the interior, especially if the PO was a smoker.
Windows – Miatas are known for eating window regulators over time and use. It’s not hard to remove the door panels and lubricate the mechanisms and cables and it will greatly extend the life of these components. Best lubricant for the channels in the vent windows is shin-etsu grease, available only from Honda.
Fluids:
Transmission – The fluid won’t be affected as much by time as use. However, it’s a good time to change it over to Redline MTL or another recommended type. It improves shifting and extends the life of internal parts.
Differential – Ditto the comments above except it takes Redline 75/90. Changing it is especially important if you’re lucky enough to have a limited slip differential.
NOTE: While you are under the car doing the trans and diff fluids, take the time to look around at all the suspension pieces for any obvious problems (missing bolts, bushings hanging out, broken pieces). Assuming your car is very safely up on jack stands (I also leave both my floor jacks engaged), don’t be afraid to grab on to stuff and shake it to see if anything is obviously loose.
Radiator – Do a complete flush and fill using a commercially available cleaning agent. Take a good, long look at the radiator. If the cooling system hasn’t been maintained on a regular basis (every two years), then chances are your radiator is going to let go at the worst possible time. You can buy a direct replacement plastic/metal radiator for under $100.00 and it is an easy task to swap it out. When finished, make sure to “burp” your radiator of all air.
Shift turret boots and oil – The two boots under the console don’t hold up well over time. They are about $45.00 for the pair and easy to change (see the garage section on miata.net). Changing the turret oil will help with the shifting effort.
Miscellaneous:
Don’t worry, I’m almost ready to shut up!
Wipers – Many low mileage cars have never been driven in the rain for a couple of 18” wipers blades from Wally World are probably necessary.
Top and rear window – Inspect and replace if necessary. On the subject of the rear window, perhaps it’s just the area I’m in but the quotes I got for replacing the rear window at an upholstery shop were almost as much for a new top if you do the install of the top yourself. If the window is just fogged, the meguiars cleaner and polish will get it back to good shape with lots (no, LOTS) of elbow grease.
Headlights – The halogens on the NA Miatas aren’t the brightest on the road. You can go the cheap and easy route and buy the Sylvania EV models as direct replacements which are considerably brighter than stock and install exactly the same way. Or, you can consider upgrading to the Hella European lights which are way brighter but require some sophisticated aiming procedures to get absolutely accurate and BTW, are technically illegal.
Lazy eyeball vents – Droopy vents are almost a trademark of older Miatas but if they bother you, there are plenty of instructions on how to fix them for free.
Parking brake – It should be within the specified number clicks for your year (see the garage section). Most aren’t because the PO doesn’t notice the change. It changes from brake pad wear as well as stretching of the actuator cable. It can/should be adjusted at two points – one is at the rear brakes themselves and the other is at the handle end.
And last, but certainly not least, ROAD TEST! Find a nice, deserted road where you can SAFELY wring your now up to date car out. Not only is it fun, but it will point out anything else that may need attention from a suspension/engine/transmission/clutch standpoint.
