Oil for a first gen Miata

Pennzoil motor oil
A

AngryScientist

Joined
Feb 16, 2011
Messages
95
Location
NJ
Just pulled the trigger on a '90 Miata with the 1.6 and about 135k on the clock.

It did not come with an owner's manual, and info on the web is all over the place. I think 10w-30 is the right choice here, correct?

I've wanted one of these forever. Finally found one with very very little rust and the engine runs like a top. Upon buying it took a 200 mile drive home and had, knock-on-wood, zero issues. Such a fun little car to drive.

Cheap thrills :)

3750EC24-847F-4225-90C6-DA000873D0AF.JPG
 
I use 10w30 or 10w40 in mine. Check your oil often, as in at least once a week. Most of these cars - including my '90 - burn some oil and you want to stay on top of that. Overheating is the death of the otherwise robust motors in NA Miatas, don't let that happen.
 
That chart feels so outdated to me, not recommending 5w-30 except in cold weather but allowing 10w-30? Most 5w-30s nowadays are built better than their 10w-30 counterparts, unless it’s a boutique oil.

I’d go with a 5w-30 or 0w-30 in this long before I’d go 10w-30.
 
Patman said:
That chart feels so outdated to me, not recommending 5w-30 except in cold weather but allowing 10w-30? Most 5w-30s nowadays are built better than their 10w-30 counterparts, unless it’s a boutique oil.

I’d go with a 5w-30 or 0w-30 in this long before I’d go 10w-30.
Click to expand...
Yep Sir. We don't live in 1990 and can take advantage of what is current.
 
Run 10w30 in my NA 1.8. It has typical lifter tick that clears after a second or two.

Yours being early you should check for "crank snout" issues.

Oil filter placement isn't the greatest, but the cars are generally very easy to work on.
 
AngryScientist said:
Just pulled the trigger on a '90 Miata with the 1.6 and about 135k on the clock.

It did not come with an owner's manual, and info on the web is all over the place. I think 10w-30 is the right choice here, correct?

I've wanted one of these forever. Finally found one with very very little rust and the engine runs like a top. Upon buying it took a 200 mile drive home and had, knock-on-wood, zero issues. Such a fun little car to drive.

Cheap thrills :)

3750EC24-847F-4225-90C6-DA000873D0AF.JPG
Click to expand...
Opinion here. I never owned a Miata. I would consider four 4–5-thousand-mile service interval Valvoline Restore and Protect first, then switch to Mobil 1 ESP 0w30 or Motul 8100 X Clean EFE. Of course, the Mobil 1 is much cheaper to buy at Walmart and possibly just as good or a better engine oil. Both of these 0W-30 are ACEA C3 and give you >3.5 HTHS.
 
You can use just about anything in that BP motor. It is so very under stressed and with the timing belt it doesn't shear the oil like some motors. It is just about the easiest mill to take care of I'd ever owned. I beat the snot out of mine with anything from 0W-20 (Street driving) to 5W-30 and 5W-40 (track days), it really never cared.

If you have any HLA ticking experiment with thicker and thinner oils. Or even Valvoline Restore and Protect, which is probably what I would use in one form or another. The HLA's have a habit of getting plugged up and that makes them slow to pump up when running and you'll get a tick. Not a problem, but it is annoying.

Of course, sometimes you'll get a hot tick as well from the oil being thin and not keeping the HLA's pumped up, so it really can be a crap shoot.

Fantastic little car with a near bulletproof drivetrain, miss mine every day.
 
Last edited by a moderator:
The_Jeff said:
Yours being early you should check for "crank snout" issues.
Click to expand...

His being a 90, unless they replaced the motor, will be a short nose crank.

He will want to have a good look at that, once they're buggered up the only reasonable fix is to replace the motor.
 
AngryScientist said:
Just pulled the trigger on a '90 Miata with the 1.6 and about 135k on the clock.

I've wanted one of these forever. Finally found one with very very little rust and the engine runs like a top.
Click to expand...
Great gem find with awesome mileage! Congratulations!
I hope to find one day something similar, but NB or NC.

Do you have any history on the services done? Timing belt and water pump might be due, if not replaced before 100K miles.
I would first access how much oil it burns (if any), which means checking up the oil every week, depending on how often you drive it.
If it burns oil and there's visible sludge or varnish below the valve cover, I would definitely try Valvoline Restore and Protect 5W-30 (for a few oil cahnges) to make sure I'm at a clean start. Mobil 1 ESP 0W-30 is very good oil too.
They are still plenty of 10W-30 oils too. Valvoline High Mileage w/t Valvoline Maxlife Full Synthetic may be a good choice too. Mobil, Castrol, Amsoil, and Royal Purple also still offer full synth. 10W-30 oils.

Definitely will stay with full synthetic oil and replace any gaskets if start leaking. Most likely if there is no current leaks, there won't be in the future too.
I would lift it up and go through all the rust spots with rust remover and eventually pain it with some undercarriage coating.
Also, it never hurts to have a thicker aftermarket coolant radiator. You can always drop in a NB engine too, if you find a decent one.

Happy throttling!
 
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This is great stuff thanks. It does look like a 0w-40 would be a great choice for this engine. I anticipate little driving in the colder months. They really cover the roads in salt around here and that's just awful for an older vehicle. I went to view many Miatas with similar mileage that were trashed by rust. I can always do engine and transmission work, but once the shell/core is gone, it's all over in my experience.

This one sat in a garage for a long time, but was driven occasionally. I know the timing belt was recently done but not much beyond that. The gent who sold it it me seemed like a pretty diligent mechanic (he had a two post lift in his garage...), so I expect most stuff is up to date. None the less, once Spring hits I intend to do a full coolant flush, transmission fluid and rear diff fluid. Brakes need doing so will flush that fluid at that time too. No power steering or AC on this little guy, so nothing to do there.
 
AngryScientist said:
This is great stuff thanks. It does look like a 0w-40 would be a great choice for this engine. I anticipate little driving in the colder months. They really cover the roads in salt around here and that's just awful for an older vehicle. I went to view many Miatas with similar mileage that were trashed by rust. I can always do engine and transmission work, but once the shell/core is gone, it's all over in my experience.

This one sat in a garage for a long time, but was driven occasionally. I know the timing belt was recently done but not much beyond that. The gent who sold it it me seemed like a pretty diligent mechanic (he had a two post lift in his garage...), so I expect most stuff is up to date. None the less, once Spring hits I intend to do a full coolant flush, transmission fluid and rear diff fluid. Brakes need doing so will flush that fluid at that time too. No power steering or AC on this little guy, so nothing to do there.
Click to expand...

Nice thing about the timing belt.

They're super easy to do (although you have to use caution with the short nose crank) and it is a non-interference motor, so if it breaks, you're just out the tow home and the new parts. Everything in the engine will survive.

The cam angle sensors like to leak. It is a standard O-ring, (#222 if memory serves), super easy to replace.

If you have a timing light handy you can bump base timing up a couple degrees for a little more low end pull. Most people go from 10deg to 12-14deg.

Clutch slave cylinders like to leak. Same with the clutch master. Both are easy jobs, although bleeding will be easier with a vacuum tool.

Spend some time looking for a good alignment tech that can put a good street alignment on it, and replace the camber bolts while you're in there, they like to stretch and cause popping noises. The updated Mazda bolt is much stronger. A good alignment will transmissionform the driving feel of the car. As good as they are stock, they're even better with a good alignment on all 4 corners.

Other than those few minor things, those cars are one of the best built vehicles of the last century. There's just not a lot that goes wrong with them, they just keep working.
 
ctechbob said:
Spend some time looking for a good alignment tech that can put a good street alignment on it, and replace the camber bolts while you're in there, they like to stretch and cause popping noises. The updated Mazda bolt is much stronger. A good alignment will transform the driving feel of the car. As good as they are stock, they're even better with a good alignment on all 4 corners.
Click to expand...
Thanks for all of this. Yea; it definitely needs a little love in the handling department. A huge part of the problem now is it's probably on 20 year old tires that suck and need balancing, but on the drive home there was a pretty notable "death wobble" at around 70mph.

The stock wheels are 14", and there seem to be very few options in the performance category. I want either UHPS or UHPAS for this car, and I dont see anything readily available in the 14" size. I may be looking for a set of 15" wheels to open up my tire options a bit, but I'm a little concerned about weight. In any event, first maintenance item is new rubber all around, if nothing else for safety. Alignment to follow.
 
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