Diff and Manual Trans oil
Thread Starter
Racer
Joined: Nov 2005
Posts: 340
Likes: 0
From: Dublin
Diff and Manual Trans oil
Do anyone run the same gear oil in their diff and their manual trans?
If I use the pump/siphon out method of draining the trans through the fill hole how much can I hope to remove? M21 just checking to how much I need to purchase
thanks
If I use the pump/siphon out method of draining the trans through the fill hole how much can I hope to remove? M21 just checking to how much I need to purchase
thanks
Melting Slicks
Joined: Aug 2005
Posts: 2,683
Likes: 34
From: Working on the car NY
In my '67 with the Muncie, I run GL4 in the gearbox. Rear axle lube is GL5 which I've read is really no good for gearboxes - has to do with it "eating up" the syncro's. GL4 is hard to obtain (for me anyway) locally. I bought a case a couple of years ago from a supplier in Pa. and had it shipped.
ps. with a siphon gun, I've never had much luck getting much out from the "add" hole - probably half a qt. If you can get it up on a lift, you would have better luck in getting more out.
ps. with a siphon gun, I've never had much luck getting much out from the "add" hole - probably half a qt. If you can get it up on a lift, you would have better luck in getting more out.
Last edited by TWINRAY; Feb 1, 2012 at 12:30 PM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
You need to get the oil warmed up first, so it will thin-out, before you will have any luck with a siphon. As stated, the higher the car, the longer siphon tube you can use so that it will flow faster. Even then, it will take a while. When it gets down to the bottom of the 'punkin', you might do better with a turkey baster and hose.
Race Director
Joined: Jan 2001
Posts: 16,221
Likes: 118
From: Matthews NC
When I changed my differential oil I used two bottles of GM rear axle lubricant and one bottle of GM Positraction additive.
I personally would not use the same oil in both the tranny and differential.
I personally would not use the same oil in both the tranny and differential.
Melting Slicks
Joined: Mar 2005
Posts: 2,838
Likes: 10
From: Austin TX
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From: Northern New Jersey
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Been doing it that way for 40 years. Just add one 4 oz bottle of GM posi lube to the rear end 
Drifting
Joined: Aug 2005
Posts: 1,372
Likes: 4
From: Springfield VA
EDIT:
Mobil1 75w90 use to say MT1 but I don't see it at mobils site anymore. Advance and other sellers still say it meets MT1 spec.
MT1 though is for heavy duty LARGE trucks trans so it does not have to say MT1 to be safe but helps if I understand correct.
So Mobil1 75w90 MIGHT work in both the diff and manual trans.
Mobil1 75w90 use to say MT1 but I don't see it at mobils site anymore. Advance and other sellers still say it meets MT1 spec.
MT1 though is for heavy duty LARGE trucks trans so it does not have to say MT1 to be safe but helps if I understand correct.
So Mobil1 75w90 MIGHT work in both the diff and manual trans.
Last edited by Marlin; Feb 6, 2012 at 09:18 AM.
