Diff oil
Thread Starter
Instructor
Joined: Sep 1999
Posts: 220
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From: Alberta, Canada
Diff oil
Just changed my diff oil. I used a little $14 pump I found at Walmart, worked beautifullly. Used Castol 75W-90 synthetic and a tube of LSD additive. (no not the drug) 
I only got about a quart and a half of oil in.
Does this sound about the right volume?
I can't find anywhere in any of my books any reference to capacity.
I only got about a quart and a half of oil in. Does this sound about the right volume?
I can't find anywhere in any of my books any reference to capacity.
Race Director
Joined: Jan 2005
Posts: 10,641
Likes: 13
From: Slidell Louisiana
Originally Posted by 91C4
I have a 91 vert and when I changed mine I bought 2 qt.s Mobil 1 rear end fluid and I had about 1/2 qt. left. The manual says 2 qts. but you can't get it all out with the suction gun..
I couldn't get two quarts in mine and I removed the batwing. I guess it's due to the fact that the rear axle capacity is 1.5qts/1.42L and 4 oz/118 ml of limited slip additive.
So if you were able to add 1.5 quarts you removed almost all of the old gear oil. Mike
Instructor
Joined: Feb 2006
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From: Fraser MI
Diff oil
Originally Posted by Snuffy
Just changed my diff oil. I used a little $14 pump I found at Walmart, worked beautifullly. Used Castol 75W-90 synthetic and a tube of LSD additive. (no not the drug) I only got about a quart and a half of oil in.
Does this sound about the right volume?
I can't find anywhere in any of my books any reference to capacity.
I only got about a quart and a half of oil in. Does this sound about the right volume?
I can't find anywhere in any of my books any reference to capacity.
Wisconsin this weekend. I will use Amsoil synthetic severe
gear 75-90wt.
Is the LSD additive necessary or should I wait to see if I get
chatter in the rear end after changing?
Thanks,
Craig
Race Director
Joined: Jan 2005
Posts: 10,641
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From: Slidell Louisiana
Originally Posted by vader86
The LSD additive IS NECESSARY.
I added the required amount of LSD additive, even though the mobile synthetic gear lube I used said, that it did not need LSD additive.Mike
Premium Supporting Vendor
Joined: Aug 2001
Posts: 5,364
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From: King George VA
Originally Posted by Craig's Polo '93
... I will use Amsoil synthetic severe
gear 75-90wt.
Is the LSD additive necessary or should I wait to see if I get
chatter in the rear end after changing?
Thanks,
Craig
gear 75-90wt.
Is the LSD additive necessary or should I wait to see if I get
chatter in the rear end after changing?
Thanks,
Craig
The additive is necessary, but... the AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 comes with additive pre-mixed in, so you shouldn't need an extra bottle. If you diff chatters, then you can add some.
While it won't hurt to add a bottle if you diff doesn't need it, it will result in the friction plates in the diff having less friction, thus your diff will have less limited slip than designed. Might not be a problem for a daily driver, but if you want maximum acceleration such as for auto-x, road racing, hard street driving or at the drag strip, you will want your diff to perform as designed. If you add an extra bottle of additive when it is not needed, the tire with lower grip will get more torque (where you don't want it) than designed.
Here is the actual AMSOIL note on the additive:
"NOTE: AMSOIL Synthetic Gear Lubes do not require the use of this additive. However, not all differentials respond the same and if chatter is noticed, the addition of AMSOIL Slip-Lock will eliminate it. For chattering differentials not running AMSOIL Gear Lube, this product is an excellent solution to the problem."
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From: Kingman AZ
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Originally Posted by rws.1
1.5 Qts is about correct for an '88.
Gordon Kilibrew "THE C4 GURU" advises to add two 4oz bottles of the GM posi-lube....
Gordon Kilibrew "THE C4 GURU" advises to add two 4oz bottles of the GM posi-lube....
He said the same thing in a class I was in. He had also advised Mobil 1 synthetic gear oil.
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From: Kerrville, Texas USA Hook 'em Horns!
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Originally Posted by rws.1
1.5 Qts is about correct for an '88.
Gordon Kilibrew "THE C4 GURU" advises to add two 4oz bottles of the GM posi-lube....
Gordon Kilibrew "THE C4 GURU" advises to add two 4oz bottles of the GM posi-lube....
I did that when I changed my diff fluid. Cheap insurance.
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Joined: May 2002
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
You can hook up a longer hose to the 'suck' side of the pump, and get more of the old fluid out. Don't bother with it now though.... you're good to go.
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Joined: Oct 2004
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From: Everett WA
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Originally Posted by Subdriver
Craig,
The additive is necessary, but... the AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 comes with additive pre-mixed in, so you shouldn't need an extra bottle. If you diff chatters, then you can add some.
While it won't hurt to add a bottle if you diff doesn't need it, it will result in the friction plates in the diff having less friction, thus your diff will have less limited slip than designed. Might not be a problem for a daily driver, but if you want maximum acceleration such as for auto-x, road racing, hard street driving or at the drag strip, you will want your diff to perform as designed. If you add an extra bottle of additive when it is not needed, the tire with lower grip will get more torque (where you don't want it) than designed.
Here is the actual AMSOIL note on the additive:
"NOTE: AMSOIL Synthetic Gear Lubes do not require the use of this additive. However, not all differentials respond the same and if chatter is noticed, the addition of AMSOIL Slip-Lock will eliminate it. For chattering differentials not running AMSOIL Gear Lube, this product is an excellent solution to the problem."
The additive is necessary, but... the AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 comes with additive pre-mixed in, so you shouldn't need an extra bottle. If you diff chatters, then you can add some.
While it won't hurt to add a bottle if you diff doesn't need it, it will result in the friction plates in the diff having less friction, thus your diff will have less limited slip than designed. Might not be a problem for a daily driver, but if you want maximum acceleration such as for auto-x, road racing, hard street driving or at the drag strip, you will want your diff to perform as designed. If you add an extra bottle of additive when it is not needed, the tire with lower grip will get more torque (where you don't want it) than designed.
Here is the actual AMSOIL note on the additive:
"NOTE: AMSOIL Synthetic Gear Lubes do not require the use of this additive. However, not all differentials respond the same and if chatter is noticed, the addition of AMSOIL Slip-Lock will eliminate it. For chattering differentials not running AMSOIL Gear Lube, this product is an excellent solution to the problem."
Thread Starter
Instructor
Joined: Sep 1999
Posts: 220
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From: Alberta, Canada
Thanks all for the replies. One thing I forgot to mention, when I sucked it out some of it was thick, gooey and lumpy. Gee I hate these technical terms. It was awful smelly too.
The new stuff I put in was Castrol synthetic. I used a additive from NAPA that was not true GM but it was for that purpose. Once I get it back on the road we'll see if it chatters or not.
The new stuff I put in was Castrol synthetic. I used a additive from NAPA that was not true GM but it was for that purpose. Once I get it back on the road we'll see if it chatters or not.