Hi all,
i would like to replace the transmission oil of my 37’ chevy master coupe. The shop manual tells me that i should use SAE 160. Unfortunately it’s not available in Germany anymore. Is there any good alternative for my gearbox?
Other forum users take 85W-40 but i guess for younger cars. Are there diffrent types of 85W-40?

Thanks a lot for your help!
Best Regards
Robert

Hi Robert,

Good transmission performance on well worn gears is enhanced by thick lubricant. You may want to experiment with mixing up your own lubricant. John Deere Corn Oil is very self leveling but might me just too thick. What if you mixed some with another fluid like motor oil, or 85W-140 gear oil? What if you mixed 85W-140 with axle grease?

My suggestions should cause more suggestions on other options!!!

Good luck, Mike

P.S. Just remember there are some areas that need to be lubricated by thinner lubricants like the bushing in the front of the driveshaft, or even the speedometer gears?

Sorry, getting confused about all the diffrent oil brands. I meant 85W-140 instead of 85W-40

I use straight SAE 140 or 600 (aka SAE 160) which are available in the USA at some places. SAE 85-140 is an alternative that might be better in colder climates. Should work but tend to leak more than the higher viscosity lubricants. Blending in a little chassis or non-fiber containing wheel bearing grease would increase the viscosity.

Chevrolet made a revision in mid 1937 and went to the #90 gear oil for the transmission. That should be readily available.
For my cars I used the 85W-140 which is "thin" when cold and has more body when hot which helps to quite the gear rattle these cars had when gear oil gets hot.

<CLICK>

Many thanks to all of you who gave me a reply or took the time to read my post so far. Also a big >>THANK YOU<< to >>chevy nut<< and >>Tiny<< who mentioned the revision in 1937/38. I did a little internet research about the different types of the SAE 90. It seems to me that the API GL-4 type is a better choice then API GL-3 type for a unsynchronized transmission. Does someone know what the right choice is?

The 1937 transmission is syncronized. Note the list says 140 CAN BE USED BIG IN HOT WEATHER in trucks. The big truck had a non-syncronized 4 speed.

I have a 3 speed non-syncronized gearbox in my coupe. Maybe it is not the original syncronized transmission!

All Chevrolet 3 speeds from 1932 and up (except 1933-1936 Standards) were syncronized....but not in first or low gear. If placing back to low gear at say 5 MPH the gears will grind. First to second and second to third are syncronized , up and down, if the transmission is working correctly.

SAE 90 is just fine for your transmission and differential.

I was convinced that 140 was better and I put it in the project car. I have recently sobered up and am now back to my original agreement with the 1941 shop manual. I'm gonna suck the molasses thick 140 out and go with 90.

It is mind boggling to put 140 in the transmission and differential solely to quieten down "rattling" gears or "enhance" service of worn gears. Might as well feed some sawdust through the filler hole while you're at it.

My two cents worth,
Charlie

Charlie I use the 140 with no issues at all...Why would you remove it???

Because the manual doesn't recommend anything thicker and because its too thick to properly flow on cold gears.

My philosophy is to use the thinest oil suitable for the need. 90 is more suitable than 140. Sometimes more is less.

Why don't you use 10w-50 in your engine? See?
Thanks for the question. It is always a such a pleasure to straighten out a Fleetliner. It almost makes me giddy with shameful excitement. :Does too. Agrin:

You're welcome,
Charlie

I do use 10W-30 in my engine because it is like #10 when cold and 10 Deg. below zero but thins out to #30 wen hot.
85W-140 is even "thinner" than #90 when cold (summer or winter) and has more body when hot. If there would have been a 85W-140 in 1941 I am sure Chevrolet would have allowed it.

Gene,

Maybe so.

Nonetheless, I think the primary selection for the weight of the oil (thiness vx thickness) is owing to its ability to carry off heat created by friction. If so, then I submit that the lighter oil will do a better job.

In any case, it would be difficult to prove that the gears failed owing to use of either weight of oil.

Gene and Mike,

My comment earlier about worn and rattling gears was supposed tongue in cheek. After thinking about it, I regret that comment because it could have been taken wrongly. Sorry and I apologize to both of you. I shouldn't have wrote that comment.

Best,

Charlie
Charlie

No problem...I don't even remember the post.

We take most of your comments as tongue in cheek any way Charlie.
Tony