Differential fluid help!
Thread Starter
Intermediate
Joined: Oct 2018
Posts: 39
Likes: 2
Differential fluid help!
Hi all!
So my cars been sitting for a couple of years and im going through all the fluids and making sure shes nice and fresh. when it came down to differential fluid and the research i was doing, couldnt find a definitive answer on what fluid i should use! with that being said would love to know what factory specifications were, and if possible! links to recommended oils/additives!
thanks!
So my cars been sitting for a couple of years and im going through all the fluids and making sure shes nice and fresh. when it came down to differential fluid and the research i was doing, couldnt find a definitive answer on what fluid i should use! with that being said would love to know what factory specifications were, and if possible! links to recommended oils/additives!
thanks!
Thread Starter
Intermediate
Joined: Oct 2018
Posts: 39
Likes: 2
Turns out I can’t get a hold of the factory recommended stuff where I live here in Canada, they’re asking almost 70 dollars cdn for the 4oz bottle of limited slip lubricant which is outrageous! Any good aftermarket recommendations?
Tech Contributor
Joined: Aug 1999
Posts: 15,175
Likes: 3,987
From: Connecticut, USA
Any GM dealership, Summit, vendors about $12-15 usd - 4 oz bottle. Lucas 90 or 85-140 gear oil should be available at most parts stores, at least in the usa it is. You should look very close at the axles to see if they are hitting the housing, check the end play in them.
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
Go to Cdn Tire and pick up a bottle of Royal Purple Max Gear synthetic gear oil. It doesn't require any additive and works with posi's.
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Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
My diff may be a little finicky, we set it up very tight on the posi clutches. I had bad chatter with GM oil even with the additive. Also tried Valvoline with no luck. What works for me is Mobil 1 75W-90 gear oil + 1 bottle of the GM additive. With that fluid it is smooth as butter.
Melting Slicks
Joined: Dec 2009
Posts: 3,233
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From: Thunder Bay
Melting Slicks
Joined: Nov 2001
Posts: 2,668
Likes: 43
From: Eastern US XX
My diff may be a little finicky, we set it up very tight on the posi clutches. I had bad chatter with GM oil even with the additive. Also tried Valvoline with no luck. What works for me is Mobil 1 75W-90 gear oil + 1 bottle of the GM additive. With that fluid it is smooth as butter.
7th Gear
Joined: Jun 2018
Posts: 7
Likes: 1
I just changed my differential fluid and used Mobil 1 75W90 LS which has the limited slip friction modifier included in the fluid. I took it out for a test drive (very short because of need to be somewhere else). I still got a little noise on tight slow turns. I did some figure eights and small circles, both directions, but still have some noise. I think it may possibly clear up after some more driving. If it is still there after 500 miles, or so, I will drain it again and refill it.
Melting Slicks
Joined: Nov 2001
Posts: 2,668
Likes: 43
From: Eastern US XX
I just changed my differential fluid and used Mobil 1 75W90 LS which has the limited slip friction modifier included in the fluid. I took it out for a test drive (very short because of need to be somewhere else). I still got a little noise on tight slow turns. I did some figure eights and small circles, both directions, but still have some noise. I think it may possibly clear up after some more driving. If it is still there after 500 miles, or so, I will drain it again and refill it.
7th Gear
Joined: Jun 2018
Posts: 7
Likes: 1
I wondered if it would be too much friction modifier to add the GM with the Mobil 1 that already has it included. Since I have only driven it about 10 miles (including many small circles and figure eights), I think I need to put some more miles on it before doing anything more. I am thinking about 500 miles. What do you think?
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
Yes, the M1 bottle says it has the friction modifier in it, but my experience with my car is that I needed to add a bottle of the GM additive anyway. No worries about 'too much' additive. There's a service bulletin from GM for some new Camaros that says to add a second bottle if the customer complains about chatter.
Last edited by zwede; Jul 5, 2019 at 11:35 AM.