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Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
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| | | | Joined: Oct 2006 Posts: 1,847 'Bolter | | 'Bolter Joined: Oct 2006 Posts: 1,847 | Just curious on thoughts of using 75W -90 oil in my transmission/rear axle, that way I can just keep one oil and pump on hand for the truck and my new car. I do know I used 80W-90 in a new car once, and it did not work very well.... | | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | What year/type transmission/rear-axle? | | | | | Joined: Oct 2006 Posts: 1,847 'Bolter | | 'Bolter Joined: Oct 2006 Posts: 1,847 | 53 3100 with original 3 speed and torque tube rearend.
| | | | | Joined: Jan 2001 Posts: 5,337 'Bolter | | 'Bolter Joined: Jan 2001 Posts: 5,337 | I really think too much can be made of oil viscosity.
Years ago my wife's Honda called for 10w-40 in the transaxle.
One of my customers had a 1960 Benz and it called for ATF in the manual transmission.
I think the only risk of using lighter oil is the potential of increased leakage.
See the USA in your vintage Chevrolet! My Blog | | | | | Joined: Jun 2004 Posts: 8,597 Riding in the Passing Lane | | Riding in the Passing Lane Joined: Jun 2004 Posts: 8,597 | I would use 85-140 in the old truck trans. & rear end. In the new car use what the owners manual calls for. In the new car you don't change it often enough that the plastic squirt containers won't work.
George
They say money can't buy happiness. It can buy old Chevy trucks though. Same thing. 1972 Chevy c10 Cheyenne SuperIn the Gallery Forum | | | | | Joined: Oct 2006 Posts: 1,847 'Bolter | | 'Bolter Joined: Oct 2006 Posts: 1,847 | I was kind of thinking it would be fine, I just mentioned the new car because I used 80-90 non synthetic, and it didn't shift real well, I put the 75-90 synthetic in and it worked flawlessly. There is simply no way to utilize the squirt bottle to fill the new car, the hole is simply buried. I change the oil often enough I want a real genuine industrial oil pump, I have about 6 of those cheap little plastic pumps all broken to some extent or another, I swap parts around till I get one to work. One of them didn't even get one stroke, I pushed it down and the bottom blew off. Right out of the box. I'm so done with them..... But thanks for | | | | | Joined: Oct 2006 Posts: 1,847 'Bolter | | 'Bolter Joined: Oct 2006 Posts: 1,847 | I was kind of thinking it would be fine, I just mentioned the new car because I used 80-90 non synthetic, and it didn't shift real well, I put the 75-90 synthetic in and it worked flawlessly. There is simply no way to utilize the squirt bottle to fill the new car, the hole is simply buried. I change the oil often enough I want a real genuine industrial oil pump, I have about 6 of those cheap little plastic pumps all broken to some extent or another, I swap parts around till I get one to work. One of them didn't even get one stroke, I pushed it down and the bottom blew off. Right out of the box. I'm so done with them..... But thanks for the input. | | | | | Joined: Feb 2004 Posts: 29,795 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,795 | Get accustomed to grinding gears, especially on downshifts. Synthetic gear lube is too slippery to let the synchronizers do their job with the heavy gears and the inertia involved with stovebolt transmissions- - - -SM-420's in particular. Use 90 weight straight mineral oil in the transmissions, 90 Hypoid lube in the rear end.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | | | |
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