Getting ready to put the race fluid in the trans...what will it be?

[Tailspin]

Right now I have Pennzoil synchromesh fluid in my 5-speed and it really does seem to work well, but I'm about to change the dipstick cover and diff cover to heavy duty reinforced options, and will be doing the final trans flush then. This box will be raced in lemons, and we killed one last race. I do NOT want to have to change it again.

So bottom line, whats the best fluid for a trans that's got the punishment of a lifetime in its future? I'm contemplating a standalone gearbox oil cooler on top of an added engine oil cooler (its an NA) I just really want this box to last.

[DenCon]

I ran Redline MTL in all my cars, including my 5-spd 99 race car, without any problems; I'm going to try Shock Proof this time.

[Salna]

We flush our tranmission fluid after every race. Anything to keep the gearbox from exploding. I think we are going to have to get a cooler and reinforced plates as well, because we've ruined our transmission already. We run Lemons/Chump in the midwest.

[Tailspin]

So that's one vote for Redline MTL, what team are you Salna?

[Salna]

Team Failcar haha. I didn't notice your location until now.

For the record we use Honda MTF right now though may try red line or industrial gear oil soon.

[Tailspin]

Been looking around for info on redline, I can't remember where I saw that shockproof was a no-no, I'll keep looking for that but in the meantime I found this thread that describes the thicker MTL-90 for hotter climates: http://www.saabnet.com/tsn/bb/900/index.html?bID=397811

[Tailspin]

OK from what I'm reading about shockproof is that it's not for synchros, unless they changed their formula because on their website it contradicts that. I'm just going to get some MTL-90 and an oil cooler, call it a day on that unless anyone else has something to say..

[Geoff Weeks]

Engine oil (SAE 50) has the same viscosity as 90 GL but handles heat better, which is why it is the prefered oil in heavy truck transmissions, I would go with SAE 40 (= to 80 GL) or 30 (= to 75 GL) if you are inclined to go with other then stock. BTW I believe that trans failures are not lube related but case related, in that the case flexes. I'd be less concerned about lube and more about braceing the case in anyway you can.

[Tailspin]

Yea probably going to be getting that steel diff cover from (pending sponsorship) hahaha

[Cark]

I talked to one of the guys from the RallyHo team up in Maine the other day, and he recommended 2 qts MTL, 1 qt of Lucas oil stabilizer, and then top it off with "whatever".

Would like to change out the fluid in my 85 soon, so may try this recipe.

[Tailspin]

ive also heard of this recipe...hmm

[ejenner]

Originally Posted by DenCon

I ran Redline MTL in all my cars, including my 5-spd 99 race car, without any problems; I'm going to try Shock Proof this time.

The shockproof is too thick. Stick with the MTL - it's the best I've used so far. I tried the shockproof and wouldn't recommend it. It's good oil but not right for the c900 transmission.

[16ValveTurbo]

Redline MTL is a common one for converting from the old dyno oil to GearBox oil, or racing application. I use Mobil 1 Synthetic Gear Oil with an additive called "Power Punch" which is a high pressure gear additive that contains Molybdenum Sulfide. This stuff really prevents wear, this stuff let a 1985 NA 900 last 9 years after the pinion bearing was expected to fail we bought it for my brother for 150 bucks from a friend. I don't exactly race my car, but I'm definitely boosting to 10psi in every gear, hehe

[Tailspin]

Put in the 2q mtl 1q lucas stabilizer, now im getting a bit of crunchyness shifting up to third...do you think this is because its a fill meant for high temperatures? This is when the car is running cool on normal roads, and i do a spirited 2nd to 3rd shift at 4500k rpm. Should I assume when the car is racing and really hot, that this will go away?

[Salna]

So now that you've raced the car with the stabilizer, what are your thoughts?

[Tailspin]

Oh yes I forgot about this post. Because of the gear crunching after putting in the thick stuff, I thinned it by taking a quart of the mixture out and replacing it with another quart of redline MTL. When cool, the trans would still occasionally crunch going into third gear, but once it was hot it seemed to be OK. I think I'll go 100% redline MTL next race, although I ran the first race with the Pennzoil Synchromesh stuff (cheaper iirc) with perfectly smooth shifting all race.

That was also a different transmission, that may have been in better shape, than this, but the problems with third gear only started after putting in the thicker fluid. It was definitely a momentum botcher going into Canada corner realizing you were not in gear yet. Id say for now, the thin stuff might work out better.

[Cark]

So you think the Lucas thickens things up a bit too much? I'm going to be changing the fluid out in my 85 (road car, not track) soon and definitely would like to know the best recipe!

[Tailspin]

All transmissions are different, and mine isn't exactly prestine...but it does seem to prefer a thinner oil. Redline MTL would probably do the trick, but I may go back to the pennzoil synchromesh stuff you can get at all the chains as it seemed to work.

[Salna]

I recently acquired a reman'd Eriksson transmission, still in its original shipping box. The case has sharpie writing on it to only use engine oil. I asked the Saab mechanic I bought it from about it, he's used only engine oil his entire career because he thinks the thicker stuff won't flow as well. I want to try industrial gear oil and an oil cooler next.

[Tailspin]

^more support for a thinner oil, although I don't think I'd go as thin as motor oil.