Muncie M20
08-21-2015, 03:11 PM
#2
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The good old fashioned straight 90 weight is no longer available, but any good 75/90 or 80/90 non-synthetic will do. There is some debate over the GL rating, but the normal GL-3 or 4 works just fine. Synthetic oil tends to leak and give synchro issues with these old-school gearboxes.
08-21-2015, 03:13 PM
#3
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2023 C1 of the Year Finalist - Modified
2015 C1 of the Year Finalist
A quality a 80-90 GL-4 rated gear oil. Probably the EASIEST GL-4 to find is at your local NAPA store by their brand name Stalube.
There are SOME gear oils on the market which claim to be rated GL-4/GL-5------------and they state that they are NOT harmful to brass metals (such as the brass syncro rings in a Muncie). Personally, I've been building 4spds (mostly Muncies) for over 45yrs and I just stay with the tried and proven GL-4 rated lubes.
There are SOME gear oils on the market which claim to be rated GL-4/GL-5------------and they state that they are NOT harmful to brass metals (such as the brass syncro rings in a Muncie). Personally, I've been building 4spds (mostly Muncies) for over 45yrs and I just stay with the tried and proven GL-4 rated lubes.
08-21-2015, 06:22 PM
#4
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I agree. Been using the Stalube products since the '70's and it's excellent stuff. Not expensive, either.
08-21-2015, 07:25 PM
#5
Race Director
GM #89021671........formerly GM #1052271. 80W-90 GL-4+ (can be used in both manual transmissions and in GM std and posi rear axles.). 23oz bottle. About $10 per bottle.
I have used this lube for over 20 years, with absolutely no issues.
GM has recently discontinued and has gone with a synthetic. I just recently purchased 6 bottles from a GM dealer over the internet, so it is still available if you look. I can provide contact info if needed.
Larry
I have used this lube for over 20 years, with absolutely no issues.
GM has recently discontinued and has gone with a synthetic. I just recently purchased 6 bottles from a GM dealer over the internet, so it is still available if you look. I can provide contact info if needed.
Larry
08-21-2015, 09:48 PM
#6
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I just go to a truck store where they service big rigs and buy what they use in 75/80 gear oil
08-21-2015, 09:52 PM
#7
Race Director
Here is the 85W90 Stalube that I recently bought online.
Buy ahead of time, before it's all gone.
Buy ahead of time, before it's all gone.
