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| | | | Joined: Nov 2006 Posts: 24 Apprentice | | Apprentice Joined: Nov 2006 Posts: 24 | I have a 1970 C-10 Chevy. with posi-traction rear axle. I am going to change the fluid. Do I need to put in any additive for the posi-traction and what # gear oil should I use? I had a Convette once that I had to use a special additive for the Posi-Traction. Thanks | | | | | Joined: Dec 2003 Posts: 2,733 Shop Shark | | Shop Shark Joined: Dec 2003 Posts: 2,733 | Any GM dealer has the lube you are looking for I think. At least they used to.
NAPA may also have it available. | | | | | Joined: Dec 2007 Posts: 96 Wrench Fetcher | | Wrench Fetcher Joined: Dec 2007 Posts: 96 | My dad worked at Chevy dealerships as a mechanic for years. I bought an old 68 Impala that had a posi rear in it, and when I drove it home, I thought the rear end was going to blow apart with each turn it clacked and hopped so bad. Dad had some small bottles of GM posi rear end additive. He said he stocked up on it just before they reformulated it. The original was made from sperm whale oil. No kidding. When we took the cover off the 12 bolt posi everything looked OK, so I just changed the oil and put in the 3 oz bottle of additive. Presto...no more noise. I put 120K miles on that car and it got me through college. | | | | | Joined: Feb 2006 Posts: 564 Shop Shark | | Shop Shark Joined: Feb 2006 Posts: 564 | You do need the Posi-additive. However, after this long, it's a safe bet the clutches in the unit are worn out anyway. You can buy new clutches and springs for pennies on the dollar compared to buying a new posi unit, and then have the unit rebuilt.
-Brad
SOUTHERN FALL GABfestOctober 6 ~ Commerce, Georgia Details here!Never Pee on an Electric Fence. | | | | | Joined: Feb 2000 Posts: 5,206 'Bolter | | 'Bolter Joined: Feb 2000 Posts: 5,206 | Does the posi still work OK? Additive will not fix one, in fact it makes them slip more if they are worn out.
Use a heavy oil if its got a ton of miles, or recommemded weight oil with a normal amount of miles. One bottle of GM or NAPA posi additive should be all you need. 80/90 would be about right.
Hit a open parking lot and do a bunch of real slow figure eights to work the oil additive into the clutches. Dad used to do this after long trips on the highway in our old wagon. The first turn or two off the highway sounded like the axle was breaking! A few figure eights and it was back to normal.
Joe | | |
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