C-1 positraction lubricant

[Larry C.]

My 1962 differential has been rebuilt and is about ready to be re-installed, so I'm double checking what is required for lubrication. According to the '62 owner's manual, a special hypoid gear lubricant should be used, and is listed as part #3758791. A few years back, I purchased several bottles (23 oz each) of the lubricant sold over Chevy parts counter - part # then was 1052271.

Have always been told that positraction units also require a small bottle of "additive", also sold by the Chev parts dept. Nothing appears that I can find in the owner's manual about this. So, was there a special service bulletin that was issued some years ago about this additive? As a side question, are there GM vehicles that also use the special hypoid gear lubricant but do not require or use the additive?

Would the differential be damaged or not operate properly without this additive?

Comments/recommendations will be appreciated.

Larry

[Joe L.]

Re: C-1 positraction lubricant

My 1962 differential has been rebuilt and is about ready to be re-installed, so I'm double checking what is required for lubrication. According to the '62 owner's manual, a special hypoid gear lubricant should be used, and is listed as part #3758791. A few years back, I purchased several bottles (23 oz each) of the lubricant sold over Chevy parts counter - part # then was 1052271.

Have always been told that positraction units also require a small bottle of "additive", also sold by the Chev parts dept. Nothing appears that I can find in the owner's manual about this. So, was there a special service bulletin that was issued some years ago about this additive? As a side question, are there GM vehicles that also use the special hypoid gear lubricant but do not require or use the additive?

Would the differential be damaged or not operate properly without this additive?

Comments/recommendations will be appreciated.

Larry

Larry-------


The posi unit will not be damaged if you don't use the additive but I HIGHLY recommend that you use it to avoid unwanted noise and posi "grabbing". It's currently GM #88900330, aka AC-Delco 10-4003. Use TWO 4 ounce bottles.

By the way, GM #1052271 is no longer available from GM. It was also used for non-posi axles which, of course, do not require the additive.

[Larry C.]

Re: C-1 positraction lubricant

Thanks, Joe, for the reply. If GM gear lube #1052271 is no longer available, what if, anything, was it replaced with?

Also, are there current market products that will serve the same purpose for early limited slip differentials?

Larry

[Duke W.]

Re: C-1 positraction lubricant

Use any brand with the API "donut" that says SAE 80W-90 GL-5. You can buy the friction modifier additive for Positration axles from NAPA, NCB4285V. There's no need to pay the high GM dealer markup for these produces.

[Larry C.]

Re: C-1 positraction lubricant

Thanks, again, Joe. You're a great source of knowledge.

[Larry C.]

Re: C-1 positraction lubricant

Sorry Duke, I had Joe Lucia on my mind from a previous response. You and Joe are both great assets to this website and your willingness to share helps us all. I think I got it right this time.

Larry