Hey Rich,
Do not run any synthetic gear oil in the 3rd gen tranny.

Chris

 

Why do you say this Chris? My trans led a long full life drinking synthetic

 

I had the most luck using Neo synth in the transmission while it was still a rotary in both The 89' TurboII and the FD.

 

I'd like to hear more about this as well.

Might be better off in a separate thread but since the topic came up...


FWIW, I've heard a few race shops say that about Mazda transmissions. I know I personally have 2 high mileage transmissions (my FD and my 180k Miata) that were fed mostly Redline MTl and MT90 synthetic. Both had a lot of bearing wear and died b/c of that. The thought is that the Redline oil is (1) just too thin and (2) doesn't coat the bearing surfaces well enough causing wear.

Some of the more successful Spec Miata guys use Motul or Swepco for their trans and diff. Some SM rebuilders advise to use non synthetic such as Valvoline and to change it often.

I'm about to switch over and try NEO after running 75-90 Valvoline b/c the shifting when the car is cold sucks.

 

DONT use redline in mazdas? uh ohhhh LOL
8 years so far in the fd and miata

 

gracer7,
You hit the nail on the head. For some reason it turns the trannies into slop and you also get high bearing wear. Peter Farrell found this out rather quickly in both customers cars and his race cars. I can hop into a car that has had synthetic in the gearbox and tell quickly by the sound and play in the tranny. I am not sure why this is to be honest, never put much thought into it. My gearbox feels brand new and it has never seen any synthetic.

Hope I answered your and Rich's question...

 

Peter Farrell told me the same in 1998 when I was running Redline oil and had a main input bearing failure at 60K. He told me that he saw this in all the trannies running redline. He installed a used tranny for me that had 30K. Since then I have never used synthetic (every 30K), just good old 75w90w tranny oil and the tranny has been fine for the last 65k.

 

I'm throwing the bs flag on this....the problem comes in when you run a GL-5 rated gear oil, which can degrade "yellow" metals in the trans over time. I run Amsoil GL-4 rated gear lube in my FD and S2000 and have for many years, both cars shift great. I also know many S2000 owners on s2ki who run synthetic in their trans and I've never heard a report of issues.

 

Because Redline sucks, it's that simple. I never see good UOA reports on it for trans fluid. Run Amsoil.

 

Let me add that most trans fluids see excessive viscosity shear in as little as 5,000 miles. Again, well documented on s2ki and another reason to change the trans fluid at least every 15k and run a quality GL-4 gear lube that resists shear. If anything, an off-the-shelf dino juice oil will break down even faster.

http://www.amsoil.com/storefront/mtg.aspx

 

in regards to your s2k comment I've also heard from two s2000 owners (one my cousin and one my good friend) that synth is the way to go on their cars. However it may be different in ours.
I just spoke with my friend today, he broke one of his axles at the track a few weeks ago, and his diff was fine. He switched to synthetic on his first diff and tranny change and hasn't had any problems (other than burning up clutches). He told me today that it seems that s2k guys that switch to synth early on in the car's life don't seem to blow diffs like the others do. At the least it is less common. My cousin who ran standard diff oil blew his just beating on his on the streets.

 

I'm not sure why it would be any different. S2KI is far more technical than this forum. People actually get their oil analyzed and post the results instead of just randomly claiming "synthetics are junk" or whatever.

 

What is the typical trans OCI for FD owners? Has anyone gotten their trans fluid anaylzed to see what the viscosity looks like after 15k miles? I think alot of people go with a 30k mile change interval, which is too long in a sports car that gets thrashed.

 

Some data points from me

PO said he changed the trans oil every year using Redline or occasionally Mobil 1 synthetic. Mostly Redline. Bearings were dead by 123k confirmed when trans dismantled for a rebuild. Rest of the trans was great and shifted nice and smoothly.

My Miata with 180k miles one owner was changed every ~15k miles. Street usage only. Bearings sound dead at this mileage but hasn't been dismantled.


Keep in mind that we are talking transmissions here - NOT differentials.

 

Hi

So what is the best oil to use on FD trans? A normal 75w90w tranny oil?

That is interesting.

Filipe

 

Some transmilssions like the one in the FD need a little more friction in the oil for the syncros to mesh and synthetic oil is generally a master at reducing friction so you'll get some grinding with fast shifts but other than that I'd think using a quality synthetic GL 4 or 5 would work fine. For track use it's probably wise to go with 80 90 valvoline dino juice because you should change it frequently and any synthetic is pricey so that's what I generally buy for my cars.

For what it's worth Peter also told me the same thing about using synthetics and that's one serious dude who definitely knows what he's talking about so if there's someone to listen to he's the man. However I shift like a grandpa so no matter what's in there I won't do too much damage lol.

There's been so much discussion about oil, water injection, OMPs etc...etc...Just remember that plenty of these cars when maintained and driven by enthusiast have gone over 100k miles and many of those miles were on a race track and or autocross courses. The most damaging thing you can do to this car is mod it and have a some jack *** tune it, that's what's killing the whales.

I'm just spewing some madness here and I know you guys will light the flame throwers but seriously stop worrying about making 400 or 500 rwhp which is completely silly for any street car. Save your money modifying the car and spend that money going to the track which will put a much bigger grin on your face than racing down the hwy w/ a sport bike just because you can.

Some food for thought: http://www.synthetic-oil-tech.com/Ge...te%20Paper.pdf

 

I'm running Mobil 1

 

I've gone threw 2 trannies in the last year, 1st tranny had normal 75-90 in it and shifted like a charm, put in some synthetic and 5th gear syncro goes out 4 months later. Swap that tranny with a low mileage jdm tranny and fill it with synthetic, 3 months later of very hard driving, 4th gear syncro goes.

Can I say synthetic was the cause here? No, but am I am from now on using non syn in my diff and tranny.

Also another thing to note, I found all my trannies using syn were very picky about fast shifts and were very easy to grind.

 

This is a great thread on something simple from other ppls experience. I need to change my fluids before race season is here for me and I have been having the same debate... dino oils it is I guess!

 

Again, GL-5 in a transmission is generally a no-no, but in differentials it's fine. I prefer to use a heavier "gear lube" in my trans that will resist mechanical shear, but I only use GL-4. The synchros can be degraded by GL-5 - well documented.

 

http://www.teamrip.com/manual_transm...tion_info.html

Use of GL-5 spec gear oil is not recommended in your manual transmission. The EP (Extreme Pressure) additives found in GL-5 will reduce the effectiveness of your synchronizers making the transmission shift poorly and tarnish them over time. How quickly will it eat up the synchros? This is dependent on both time and temperature but it's a gradual process. However, it should also be noted that if you are wanting an oil that does provide higher film strength and added protection against gear & bearing wear, you may consider using a GL-5 spec gear oil. Just remember that it will not shift as good at the high rpms and that it will oxidize the synchros over time.

 

Some people think that oil analysis are the end-all-be-all. It's just data. The interpretation of data is the key. Whether you need an analysis for making interpretations... I'm not so sure. I mean we've been driving vehicles for over 200 years without oil analysis. I feel like everyone jumped on board with analysis simply b/c they could (~20.00$).


Oil analysis are great for detecting coolant leaks into the oil.. besides that I think they're silly.... and often outside of any reliable statistical significance level and/or reliability bounds . I'd show you the link but I'm too lazy to hunt it down.


http://www.bobistheoilguy.com/forums...s.php?ubb=cfrm

 

No flamethrower here but it's not been my observation that many FDs get anywhere near 100k on 1 engine. I think most start to experience significant engine problems in the 70-80k range. Obviously it'd be a bell curve with people in the sub 70k range and those in the above 80K area.

I just wanted to toss in my .02 on the FD engine lifespan.

 

As I recall in the manual it states to use GL 4 or 5 75 90 or 80 90 if you're in a warmer climate but I also may be mistaken but hopefully nobody reads this thread and decides to switch from what has already been working for them.

 

Yep, here's the FSM text:

Specified oil:
Grade: API service GL-4 or GL-5
All-season: SAE 75W-90
Above 10°C (50°F): SAE 80W-90