what is the best oil to put in my T5 trans?there was dextron in it when i bought it and ppl told me to run gear oil like 80W90 or something like that.

Stick with the ATF. GM would not have put it in there in first place if it didn't belong. Gear oil caused premature wear of the blocker rings in my T5.

Where abouts on the Island are you from? I was just back on the Cape last month for vacation. I'm originally from Florence.

most manuals tell you to use the ATF in the Manual transmissions. so yea. stick with that.. there are ussually good reasons they do that.

from cape north bud, i don't know anyone from florence though,except Billy Young,but who on the cape doesn't know him haha.thanx 4 the reply though,just want to put the best back in

Sorry for resurrecting this post, but the advice given is somewhat innaccurate and may cause somebody's T-5 damage.

The '83 to '87 Camaros had the NWC-T5 (NonWorld Class T-5) or sometimes referred to as the STD-T5 (Standard T-5) transmission. This tranny's blocking rings used brass (some say bronze) synchronizers.
This tranny did use 70W gear oil.

The '88 to '92 Camaros had the WC-T5 (World Class T-5) transmission. This tranny's blocking rings use fiber synchronizers. These required the use of ATF fluid (Dextron II) as gear oil could cause them damage.

Z28er had an '84, and if the tranny is original (NWC-T5), it would have taken 70W gear oil, not ATF.

ok my tranny is original and there was dextron in it when i bought the car.frigg knows it works well so thats what will be in it

Could you be thinking about the '82-83 4-speed cars? My father-in-law's 1987 IROC had dextron in it as well when we changed the fluid for the first time in 1989, I remember it distinctly because we had to go swap the gear oil we had purchased for this and had to bum a ride from a nieghbor! lol

This is only regarding the T-5. There is a lot of confusion out there regarding the T-5 due to the different kinds. Many people aren't even aware that the 3rd gens ran two different kinds. This can often result in people putting the incorrect fluid in. Many just go with what was in there previously, but that is just assuming that the previous person got it right.

In your case (and others) that have found that their NWC T-5 tranny had ATF in it, there will likely be no harm done. But doing the opposite (putting gear oil in a WC T-5) can cause premature tranny failure (see why in my post above).

If your not sure what you have, or if you think your T-5 may not be the original, be sure to accurately identify what type you have. If in doubt, I would try using ATF as it's more friendly in the NWC than gear oil is in the WC. One thing there seems to be no debate ove is that gear oil in a WC is NOT a good thing.

There are tons of info out there regarding this issue. Some place on the net that might also help explain this are . . .
https://www.thirdgen.org/forums/tran...dline-mtl.html
http://www.jalopyjournal.com/forum/a...p/t-71009.html
http://www.moderndriveline.com/Techn...t5_history.htm
http://www.moderndriveline.com/md_fa...shtml#02137777
http://www.jalopyjournal.com/forum/s...d.php?t=132271
Here's a good debate that goes both ways. (as this topic frequently does )
http://www.jeepforum.com/forum/archi.../t-222460.html

Well, I did some checking and you are indeed correct - NWC T-5's use 70W since their are no bearings under the 1st, 2nd, and 3rd gears. Now here is the mystery - my father-in-laws IROC is a 1987 LG4 with what we assume to be a NWC T-5. He bought it new January 1987 and we did the first transmission fluid change in December of 1989 (on my Christmas leave from the Marines) and the OEM fluid was very clearly Dextron II (red color, unique smell, very light viscosity). This car should have had gear oil in it! I'll check into his car some more, but I know it's all factory original...

The factory shop manuals list ATF for all the T5s. I've seen two non-WC T5s with gear oil that was reportedly the factory fill.

my shop manual says 80/90 weight gear oil

The GM shop manual for my 85 IROC calls for ATF.

JamesC

There is a GM decal on my T-5 that state 'use ATF only' so I'm using Synthetic ATF in it

I've been told by two people running in American Sedan that they use Mobil 1 5W-30 in their T5s. Could that do any harm, espicially if the car isn't a daily driver?

Do NOT use gear oil or motor oil in a WORLD CLASS T5.

ATF will work fine in ALL T5's.

To get technical NON WORLD CLASS T5's call for 70W gear oil, BUT ATF will work with no problems in the NON WORLD CLASS T5.

Not completely accurate; I just read the 84 & 86 Factory Shop manuals and they both called for the T5 to get DEXTRON II ATF...

In our shop we run Dexron III/Mercon in ALL T-5's. Using ATF is the only way to be sure you won't do any harm.

I also run a Lubeguard additive with the ATF in my T-5.

My T5 came out of a 84 Z28 when a removed the fluid it was gear oil my local dealer tells me to put atf fluid but i have rebuilt the tranny and the synchros are brass/cooper. There's no bearing on the 1,2,3 it's all brass bushing. I will put some gear oil in it since this tranny have been abused and still works great. Great work Iroctopless it's the first REAL good information that I see for these tranny

I had a 1983 Z28, which I bought in 1986 and now have a 1985 IROC I bought in 1999, both T-5. When I went to change the transmission oil in the '83 I was shocked to find this watery red stuff in it instead of real gear oil. I had a 1983 Helm manual and it clearly specified gear oil. Fast forward to the '85. This one had ATF in it and the Helm manual for 1985 says Dexron II. Presumably in 1986 shops were standardizing on ATF for these transmissions, no matter what was originally called for.

So here's what I think. By 1985 GM was specifying ATF for manual transmissions because the low viscosity improved gas mileage by 0.001 MPG, helping their CAFE numbers.

well from reading all the post here, I think I will run the atf instead of the gear oil. I just bought a 84 z28 305 H.O. and no manuals of any kind and easier shifting sounds good to me. I have no clue whats in there now, but I do know it was rebuilt.

What he said, you dummies!

SyncroMesh By GM is a good stuff in my opinion

ATF is that mean
automatic transmission fluid ??

Yes.

JamesC

Hey, for all you guys saying the NWC T-5's take 80/90 gear lube....Here's a challenge. Go ahead and put that gear oil in there, and write back to everyone about how smoothly it shifts.

-You'll be changing it for Dextron III before you know it....

My cheapo Haynes manual for my '83 says to use 80/90 gear lube....after trying it, I'm convinced it was a typo - I think they were referring to the 4 speed saginaw.

As said above, gear oil in any T-5 is not a good idea.

You also don't want to use synthetic ATF from what I've heard because it will burn up the syncros. At least in the World class.

the input shaft has a drilled hole through the center that's about maybe 3/16 in size for lubrication. Gear oil will not pass through efficiently use only ATF!

1. This thread has been buried for 5 years.
2. The fluid in the T-5 specification depends on where you look. I have a digital copy of what is essentially the universal T-5 rebuild/repair manual. It calls for any of the above depending on the year break and manufacturer. 80W gear oil, 5W-30, ATF, it doesn't matter. I can tell you for sure my 87 owner's manual calls for 5W-30. I bought an 84 NWC which clearly had some sort of oil for its entire life (pretty black inside), and an 85 clearly with ATF (VERY clean inside). So it's up to you as long as you DO NOT use anything but ATF in the WC.

I had an actual owners manual for my first 84 and it said Dextron II...and it had ATF in it after we pulled the transmission after I wrecked it (this was in '98)