Hi, i have a 88 world class T-5 from a 88 iroc, I was wondering what is the best fluid to use in it? I have mobil 1 dex 3 atf in it now, i have also used castrol syntec dex 3. What do you guys recomend, the manual calls for dex 2. I am going to be putting a new clutch in and going to change the fluid while it is out and was thinking of useing either amsoil,mobile 1 or castrol syntec. Is the gm syncomesh any good and could I use it? I road race the car and drive it on the street it is behind a 350. I want the trans to hold up for awhile. Thanks

 

hey, ive heard that dex fluid is recomended but that gear oil (80-90) is inter changeable. Anyone have any answers? My wc-t5 was filled with 80-90 when I found it and Ive not had any trouble so Im leaving it. I have heard that dex is better for narrow passages in the newer t5s.

 

Royal purple say they make a special formula to use instead of atf.


keep it coming.

 

Scooted45, if your trans is an 86 model like your car, it's not a wc unit, which means gear lube is fine. If you do in fact have a wc trans, I'd recommend changing it back to ATF. The wc trannys have fiber clutch linings in the synchro assemblies, which are the same material used in automatic trans clutches, so that's why they call for ATF instead. Gear lube will destroy the clutch linings eventually if it's a wc unit.

 

The royal purple stuff is suppose to take care of teh clutchs but is a little thinker then atf.

 

What is everyone running these days?

 

The T-5 FAQ sticky at the top of the page provides some interesting/confusing info on fluid types for different years.

JamesC

 

Any kind of ATF is all about the same, in this application.

Synchromesh will work fine too.

What kind of fluid you use isn't going to make any material difference to the life of the trans. Won't keep the case from stretching or the gears from shattering. Put that fantasy out of your mind. Only thing that different fluid MAY do, is affect how it shifts (by way of its interaction with the clutch material on the blockser rings).

 

I have Castrol syn tec in there now, Dextron 3 Should that be ok? The fluid has been in there for a while but there is not many miles on it, Maybe I'll just top it off with Syn tec instead of replacing it all with amsoil or something.

 

You're very likely not using the car in a way that warrants using anything more expensive than regular cheap Dexron III.

 

I figure For the 3 Qts I would need It's ok to spend a few extra bucks, How often should it be changed.

 

With the WC model, if you run good old ATF, you should be just fine. WC T-5's have a paper type clutch lining on the forward gear synchros, which is the same material used in automatic transmission clutches, so ATF will keep the synchro clutch material in good shape. As far as any of the fancy additives out there, that's up to you. You can use them if you want to, but it isn't totally necessary. Synchromesh fluid works really nice in the newer manual trannys, but I'm not sure if it has anything in it that will protect the clutch material. You'd have to ask somebody about that.

 

When mine stert making noise and getting hard to shift I drained out the ATF and went to lite machine oil. I wark at a power plant and have acess to all the stuff the auto parts stores don't sell. I've put 10000 mile on it and it's noisy but still working fine. I have an 02 firebird with a T5 in it is that the same tranny your talking ab out? What is the differance between a WC and a Non WC?

 

Well, one of the main differences between the WC and non-WC is those clutch linings in the synchros. Only the WC uses them, the non-WC uses the old tried and trued full brass synchros. The other big difference with the WC is it uses tapered style bearings on the countershaft instead of the non-WC's straight, pencil type ones, which makes it somewhat stronger. As far as fluid, I mentioned the Synchromesh for basically the same reason you switched to that light machine oil. Synchromesh is a very thin viscosity fluid, which helps the trans to shift really slick, even when it's ice cold outside. I have a Tremec TKO in my 69 Camaro, and Synchromesh is what Tremec recommends using in them, and I gotta admit, I can pretty much shift it using only my fingertips! Compare that to my original Muncie 4 speed that uses 90 wt. gear lube. Shifting that old Muncie when it's 10 degrees outside is a challenge until the trans gets warmed up!