Miata Maintenance Info

Vincent Keene · **Posted:** Tue Apr 13, 2004 2:10 pm

OK guys I'm now getting around to some of the more obscure (to me) maintenance items on the Miata. Fluids in particular this go round. Since I don't know what/when the PO did, I'm planning to change the transmission and rear differential fluids. Car has 70K on it now BTW.

After reading way to much on Miata.net I've discovered one thing. These jokers, while they may know their stuff, have a concensus on absolutely nothing. Some say do this, some say do that, some say...well you get the picture. :banghead:

From reading MANY posts I've found the following info:

Manual transmission fluid ---- (GL-4) Redline MTL or MT-90, Royal Purple, Mobil 1.

Rear differential fluid ---- (GL-5)75W90 Redline 75W90 OR 75W90NS, Royal Purple, Mobil 1, or stock dino oil.

What do you other fellow Miata owners use? Mazda recommends changing these fluids every 30K which seems excessive to me, but I don't know. In input is appreciated.

Diane Hall · **Posted:** Tue Apr 13, 2004 2:33 pm

Mine both have Redline MTL in the tranny, and Redline 75w90 in the diff.

Good source for Miata questions (at least it was for me) is Carl Cason at Sports and Compacts. I'd bet he'd give you yet another opinion.

Dustin Fredrickson · **Posted:** Tue Apr 13, 2004 2:49 pm

Vincent, I'm in the same boat with our "new" Miata.

FWIW, I was planning Redline MTL in our tranny as well. I've heard mixed opinions in the CRX community on it - specifically causing premature wear on the sychros, so I actually used Honda MTL in my CRX (which worked great, btw). BUT, the newest CRX tranny is 13 years old, so take it for what it's worth. I also haven't heard anything of the sort for the Miata, and there are plenty of people happy with Redline.

Hadn't decided on the diff yet, though. Let me know if you find anything "interesting".

Chuck Frank · **Posted:** Tue Apr 13, 2004 3:11 pm

I use Redline in both the Miata and the Celica's transmission and rear end.
Just be sure to use the one that is right for the type rear dif you have in your Miata, i.e. open or Torsen, in 1.8's, open or viscous in 1.6's.
I've had no shifting issues with the Miata tranny. I changed the oil at <10K and haven't changed it since (70K now).

Vincent Keene · **Posted:** Tue Apr 13, 2004 3:19 pm

Dustin Fredrickson wrote:

Redline MTL in our tranny as well. I've heard mixed opinions in the CRX community on it - specifically causing premature wear on the sychros

From what I've read using a higher GL number is what causes premature damage to the synchros. The Miata's are supposed to use a strict GL-4 grade like Redline as opposed to some other synthetics which are rated at GL-4 to GL-5 like Mobil 1.

My tranny may feel a bit "notchy" I guess on the 1-2 shift, but compared to my Z-24 it's smooth as silk! I'm more concerned on the sounds other say they get from the transmission after switching to Redline or whatever.

Also I've read what seemed like a zillion posts on oil weights, brand, type etc. and also asked several THSCC Miata owners. Guess what? Everyone has a different story to combat the HLA problem. I finally decided to use Pennzoil 10W30 (non-synthetic) because I've used it in every car I've had. Works fine and have no HLA noise at all unless it's run hard in several back to back runs. Even then it's not bad and quiets down in a few minutes.

Vincent Keene · **Posted:** Tue Apr 13, 2004 3:23 pm

Chuck Frank wrote:

Just be sure to use the one that is right for the type rear dif you have in your Miata, i.e. open or Torsen, in 1.8's, open or viscous in 1.6's.

Again from what I've read the Redline 75W90 is supposed to be the one to use on most everything I guess unless you have the old 1.6 viscous LSD. :whoknows:

So Chuck you agree that changing those fluids every 30K seems a bit much?

Diane Hall · **Posted:** Tue Apr 13, 2004 3:26 pm

[quote="Vincent Keene]I finally decided to use Pennzoil 10W30 (non-synthetic) because I've used it in every car I've had. Works fine and have no HLA noise at all unless it's run hard in several back to back runs. Even then it's not bad and quiets down in a few minutes.[/quote]

They [almost] all tick some. Consider it an "oil change alert" noise. When it's ticking all the time, check the last time you changed the oil. Bet it's getting close to time again. Change it and the tick should return to the "just at start-up" or "after hard back to back runs" tick.

When mine ticked ALL THE DAMN TIME, I had the lifters replaced. IIRC, there were 4 bad ones.

Diane ~ who's car used to tick all the time

ps - down there I always ran 15w50 M1. That has seemed to be a bit heavy up here on the cold mornings. It's first 10w30 in there now.

Chuck Frank · **Posted:** Tue Apr 13, 2004 3:42 pm

The Miata tranny is a tight one, so I think the change schedule is based on dino oil which is more heat sensitive. If I was still racing the Miata, I'd be changing it ~ every 40K, but with only street use I may not change it again until next year or let the next guy do it if I trade it for a new one.
I had the Celica tranny replaced in Aug last year and put redline in the new one as soon as I brought it home. I always use the grade of lubricant the manufacturer calls for, they know more than I do. Mobil1 and Mazda OEM filters only in the Miata.
The HLA cold ticking is normal in the pre 99 engines due to cold tolerences needed to reach correct spec when at operating temp, as long as not excessive when hot it's OK. My 99 has solid lifters so it's not an issue for me.

Vincent Keene · **Posted:** Tue Apr 13, 2004 3:51 pm

Chuck Frank wrote:

The Miata tranny is a tight one, so I think the change schedule is based on dino oil which is more heat sensitive.

For my continuing education here, what the heck is Dino Oil anyway? Sorry, but all that comes to mind is a certain Flinstone's character.

Diane Hall · **Posted:** Tue Apr 13, 2004 3:56 pm

You're close with the Flinstones.

Oil made from Dinosaurs.

Dino - pronounce it like the thing you take a car to to find out how much horsepower it has.

Adam Ligon · **Posted:** Tue Apr 13, 2004 3:57 pm

Vincent Keene wrote:

Chuck Frank wrote:

The Miata tranny is a tight one, so I think the change schedule is based on dino oil which is more heat sensitive.

For my continuing education here, what the heck is Dino Oil anyway? Sorry, but all that comes to mind is a certain Flinstone's character.

Dino, as in non-synthetic. Dead dinosaurs turned into oil, well not really it was more of a biomass thing but that's a whole other topic

jimpastorius · **Posted:** Tue Apr 13, 2004 3:57 pm

Someone you probably want to ping on this is Eric Peterson. I do not think there is a Miata in the club that has endured as much has his old one did. Whatever he used, I would copy

Eric warned me in my first year not to pay to much attention to the message boards.

Vincent Keene · **Posted:** Tue Apr 13, 2004 4:05 pm

jimpastorius wrote:

Eric warned me in my first year not to pay to much attention to the message boards.

Ain't that the truth! I'm using any info I find on Miata.net as a guide only. That's why I'm posting here, to find out the real answer.
:help:

Chuck Frank · **Posted:** Tue Apr 13, 2004 6:07 pm

That's the reason that most of the hard core Miata peeps left M.N and formed TEAM POINTLESS. All the Whine and cheezers stayed there. :roll:

Frank Catena · **Joined:** Wed Aug 27, 2003 1:08 pm **Posts:** 418

My $.02

Transmission - Redline MTL is a bit short of the spec so I use MT90. IMHO the Flyin Miata folks know the car as well as anyone. They say MTL will work too.

Diff - Redline 75W90 (GL-5)

Most manual transmission do *not* want a GL-5 oil as it will wear out the synchros quickly.
Now for blinker fluid, I definitely use dino juice.

Frank

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