Rear end dope.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
Not trying to start an argument here, you can do want you want its your car.
But being old school, I believe synthetics have there place. And I believe that synthetics belong in the 2000s models. Seems like when people try to run synthetics in old cast iron situations with old school gaskets, things go wrong. A year from now you maybe asking why the rear axle leaks and chatters from synthetics.
I will stick with what GM still recommends for 40+ yrs:
2 bottles of GM rear axle lube.
1 bottle of GM posi modifier.
But being old school, I believe synthetics have there place. And I believe that synthetics belong in the 2000s models. Seems like when people try to run synthetics in old cast iron situations with old school gaskets, things go wrong. A year from now you maybe asking why the rear axle leaks and chatters from synthetics.
I will stick with what GM still recommends for 40+ yrs:
2 bottles of GM rear axle lube.
1 bottle of GM posi modifier.
Last edited by HeadsU.P.; Mar 17, 2018 at 04:15 PM.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
IDK. But I found the bottles on Summit Racing and even Amazon sells it. Watch for different part numbers on the bottle. Not sure whats up with that. Maybe somebody knows the difference on here.
I pre-mix the two bottle types into another bottle which is clear and has the nozzle tip on top. (similar to a ketchup squeeze bottle) Then fill the differential with the mix. That way you don't have to explain to the cops why you are doing figure 8s in a parking lot.
Add: According to Amazon the GM bottle is 80W/90 wt. $17 free shpg.
Summit is $10 + shpg.
I pre-mix the two bottle types into another bottle which is clear and has the nozzle tip on top. (similar to a ketchup squeeze bottle) Then fill the differential with the mix. That way you don't have to explain to the cops why you are doing figure 8s in a parking lot.
Add: According to Amazon the GM bottle is 80W/90 wt. $17 free shpg.
Summit is $10 + shpg.
Last edited by HeadsU.P.; Mar 17, 2018 at 05:25 PM.
Melting Slicks
Joined: Sep 2004
Posts: 3,223
Likes: 666
From: Northeast
The expert on the forum says to use 85/145. Post #4 https://www.corvetteforum.com/forums...ery-black.html
I bought 2 bottles of Lucas 85/145 and a 7oz bottle of the additive.
I bought 2 bottles of Lucas 85/145 and a 7oz bottle of the additive.
Last edited by BKarol; Mar 17, 2018 at 05:11 PM.
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Le Mans Master
Joined: Oct 2007
Posts: 7,444
Likes: 970
From: Tennessee/Rhode Island
I have been using either Mobil 1 or Amsoil 75W-90, both full synthetics, since 1990 (28 years now) without any GM additive, changing it every 8-10 years and have had zero issues with the differentials operation, sound, no leaks, no chatter.... Nothing. IMO Dino gear oil with additive is a safe bet, but modern synthetics are a better bet.......
Why anyone would use "old school" lubricants today when superior synthetic lubricants are available is beyond my scientific education unless cost is an overriding concern.
Why anyone would use "old school" lubricants today when superior synthetic lubricants are available is beyond my scientific education unless cost is an overriding concern.
Last edited by jb78L-82; Mar 18, 2018 at 06:49 PM.
Safety Car
Joined: Oct 2004
Posts: 3,725
Likes: 5
From: Minnesota
I'm still running dino in my rear but will be switching to Mobil 1 synthetic after I get it rebuilt. Mobil 1 synthetic gear lube SHC 634 has saved me tens of thousands of dollars and a lot of aggravation in my business. I have around 80 different gearboxes running daily and failures are almost unheard of. Was not the case with dino!
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
I'm still running dino in my rear but will be switching to Mobil 1 synthetic after I get it rebuilt. Mobil 1 synthetic gear lube SHC 634 has saved me tens of thousands of dollars and a lot of aggravation in my business. I have around 80 different gearboxes running daily and failures are almost unheard of. Was not the case with dino!
Safety Car
Joined: Oct 2004
Posts: 3,725
Likes: 5
From: Minnesota
I also run 8 two stage 7.5hp air compressors. Synthetics in those have eliminated heat related issues with the pumps as well. The chinese motors on the other hand...
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
Something changed your mind in ten yrs.