The Stovebolt Site Forums The Shop Area Engine Shop HELP! Gear lube oil for a T5 transmission?

Help! I have been told to use anything from ATF to 80-90 gear lube to 10-40 motor oil. The transmission is a 1983 S-10 manual 5 speed or T5 and I have it in a 53 Chevy truck with a 261 engine.
Could somebody tell me what gear oil to use?

Thanks

I just rebuilt my son's 88 Trans am. 82-84, 80w-90 gl, 85-92 dexron. I think an s-10 would use the same.

3600Chevy,

I rebuilt my sons T-5 in his S-10 pickup. I had the same question. There are two different transmissions, World Class (WC) and Non-World Class (NWC). They have different synchro sleeves I believe. One has brass and the other Kevlar.

According to the assembly manual, the NWC uses gear lube and the WC uses ATF. These lubricants are compatible with the synchro sleeve material.

On the other hand, if you read all the dope on the 'net', almost everyone uses ATF as the heavier gear lube causes the transmission to be stiff and difficult to shift, especially when cold.

ATF has one of the highest viscosity index ratings of any oil made, so whatever box you have, this oil would certainly not lead to its destruction.

Lots of folks on this site have installed this transmission in their trucks, so I'll bet you get some hands on advice in short order.

Stuart

After doing my homework and checking with several performance transmission builders....the recommendation was for 70w gear oil in a NWC T5 and ATF in the WC boxes. Based on that, I've been running 70w in my 85 NWC .72 OD T5. The transmission has shifted with no issues. At 3K I drained the box and filtered the oil in a search for any brass from the synchros.....the oil showed no evidence of any metallic residue. I'm currently at 8000 miles with no issues.

Stuart mentioned "stiffness" in shifting and on several mornings when the temps got down into the 30's and 40"s you can feel the extra resistance until the engine/tranny heats up. However, the T5 has never ground between shifts, even on the coldest mornings.

I recently picked up a NWC T5 (brass synchros) from behind a 305 cid Camaro which had been run on ATF. In draining the box and filtering for metallic residue I found none. In opening up the box to make the hybrid conversion I noted that the synchronizes showed no wear/damage.

So what oil am I going to run in this NWC brass synchro hybrid transmission? 70w synthetic gear oil. However, this is primarily because our normal temperatures are higher than average, and I'm going to be running it behind a more powerful engine. Do I think ATF will lead to premature failure in a brass synchro NWC transmission? I don't think so, although the performance transmission builders disagreed.

I'm sure there are some out there that are running ATF in their NWC T5's that will have insights to add. One thing absolutely for sure....if you're running the synthetic synchro/needle bearing WC T5, ATF is the way to go.

Dave

I running 10w-40 synthetic motor oil. My transmission rebuilder said it was best.

I think the longer this post is up on the board, the longer you will get opinions on what to run in the T-5 tranny you have. Here is my two cents.
I'm running a 85-86 S-10 T-5. When I wanted to find out what to run in it, I came to this board and at that ime I never could get a definitive answer - like this thread. I decided to go to eBay and by an Owner's Manual for an 85 S-10 Blazer and see what the manual said. It said ATF Dexron III which is now Dexron IV.
Case closed.

After all the recommendations and the additional research on the internet I have decided to use 70w gear lube. Which has the same viscosity of 5-30 motor oil but will not break down as quickly as motor oil. ATF is thin, works well at low temps, and is good for a slight decrease in drag [better economy]. But I think the 70w gear oil would be better for shifting and wear.
Thank you all for your advise.

I just had a conversation with Corey Crump at Standard Transmission in Fort Worth. Standard has been in business for a many years and they set up at most all of our local swap meets. They are representatives for Hurst Performance and work on and carry a complete lines of transmissions and parts including the Tremac and all of the Borg Warner transmissions, including the T-5's we use.

I asked Corey what oil or grease they recommend as a lubricant for the T-5. He told me definitely ATF because the construction passages and tolerances are so close on the T-5 that oil of any weight will just not flow into these passages to lubricate the transmission. I questioned him about gear oil and he said "No!"

Everytime I get into this conversation, I always end up with the same answer and I would recommend that those of you who refuse to accept ATF as being correct for your T-5 rethink your approach to these transmissions and use what is recommended by the peole who build them, use them and rebuild them.

ATF is the correct ;ube. I have the '85 S 10 manual handy (seeing as I own an S 10), it says ATF. The lube spec books at work say the same thing for all applications of the T5, exept for the '87 Firebird/Camaro, which calls for gear oil.

Ditto on the ATF. My T-5 is an '89 NWC and after listening to differing opinions from all the "experts" I decided to go to the "horses mouth" as they say, the owners manual. Sure 'nuff, right there it says ATF. You can find a lot of these manuals at your friendly corner library.

i was told by the tramsmission shop that built my T-5 Hybrid to use Redline MTL 75-90 http://www.redlineoil.com/products_gearlubricants.asp?categoryID=7

Synthetic Manual Transmission Lubricants

Red Line Oil's MTL and MT-90 are designed to provide excellent protection and improved shiftability for manual transmissions and transaxles, having cured the problem of hard shifting in thousands of transmissions with shifting troubles. How? They have the appropriate coefficient of friction for most manual transmission synchronizers (many gear oils, engine oils, and ATFs are too slippery for proper synchro engagement). And, the wide viscosity of MTL and MT-90 allow proper shifting over the entire temperature range which the transmission will experience. The synthetic base oils used have a very high viscosity index which provides relatively constant viscosity as temperature changes. MTL is a low 70W at very low temperatures and a high 80W, nearly an 85W, at elevated temperatures, providing adequate viscosity to prevent wear and deaden gear noise. MT-90 is a thicker 75W90 version of MTL. The shear stability and oxidation stability of these products are excellent, thus the physical characteristics of Red Line MTL and MT-90 will change little with use.
my tranny was built by a shop in sacramento http://www.merchantcircle.com/business/Manual.Transmission.Warehouse.916-441-2712

With all due respects, Jim, I don't see any reason for me to use anything except what is recommended by the sources quoted in the last three posts, and when the Chevrolet S-10 Handbook states that the product to use is ATF, my question is answered.
I just thought I would run the question by one more time because I was considering a change to oil, but I don't want to damage my T-5.
Thanks, everybody!

I spent a lot of time researching what oil to use in my t-5.I called GM service centers and asked them what i should use,they said ATF.
I purchased a couple of different s-10 factory manuals off of ebay and they say use the ATF.
I called several transmission shops and the rebuilder of my t5,they all said ATF.
Do a search on this subject and you will come up with pages to read.

I agree with joe,follow what the manuals and manufactures say.

"A house is built with boards and beams, a home is built with love and dreams."

Jim -
Are you a homebuilder?
Joe

Joe,I think you meant Tim.I am not a home builder.I read that somewhere and it stuck into my head.

Use ATF in your s-10 t-5 transmissions.

'''''' With all due respects, Jim, I don't see any reason for me to use anything except what is recommended by the sources quoted'''''''

you asked

It doesn't bother me any

Sorry Tim - I knew better, I have read plenty of your posts. A slip of the mind resulting in a slip of the finger.

Tim, I like that little phrase! If I ever speak it, I will give you credit!

Joe

Joe,I can't take credit for it,thanks anyway.

ATF in the s-10 t5 trannies !