Dalannex

I am going to be changing the oil in my rear diff. I know I need 24 oz. of gear lube and 4 oz. of posi additive, but what wt. do I use for gear lube? Is it just SAE 90 or what? And, is posi additive something that is made by a number of companies, or do I have to get GM? My Chilton's manual (worthless) says I need GM part no. xxxxx. :rolleyes: Now what good does that kind of information do me? I don't know why it doesn't say what kind of oil it's supposed to have. :cheers:

Smokehouse69

I'd use GM rearend lube, you can get it from any GM dealer it only cost about $4.00 for qt. Also only use GM positract additive, don't go with the stuff they sell at parts stores.

1LE

Stay with the GM lube. There are two different part # for the rear end lube. I know my 4gen Camaro's use a different lube than the Vette, same posi additive. Check with your local GM parts man for the correct lube.

GaryS

Only two choices in my book: GM brand rear lube or Mobil 1 synthetic gear lube. Either one gets two bottles of GM brand positraction additive. BTW, I prefer the Mobil 1.
Gary

Dalannex

I was afraid you would all say that. Now I have to go to my local GM dealer and have them order the stuff. (They really suck!! They don't stock anything :mad ) I suppose I could go for a 60 mile drive, but I kind of hate to do that for a couple of quarts of lube. Oh well, guess I'll do this job next week. :rolleyes: :) Of course, I need to go to "the other" GM dealer anyway, my local dealer told me they don't show the battery connector on the distributor on my vette, and that it must be discontinued. You know the one, it's white plastic, single spade terminal, all GM's with distributors have them and they all have the tab that locks them on broke off, but the local chevy dealer doesn't know anything about it.

-Justin

ken welch

I have a 1973 that had original fluid in it. When I rebuild the differential, I replaced the fluid with new GM fluid. After long trips the posi clutches "dried out." People told me the "new" fluid is not as good as the old fluid. I drained the differential and replaced it with Red Line and a bottle of posi fluid. No problems for at least a year now.

Frank75

Well...

Why don't you buy on-line? Support Zip - they support us! You'll have everything you need in 2-3 days and you know it'll be right.

69er

Exactly what happen to me with my rear rebuild.
Went to Amsoil synthetic rear fluid and problem went away immediately.
I now use synthetic in the engine,th400(in a couple of weeks) and rear.
I was told the new posi clutch packs are different along with since the GM posi additive isn't whale oil anymore it isn't as good.

Dalannex

I changed the oil today. The local Chevy dealer happened to have the posi additive. He said the reason they have it is that the local John Deere shop buys the stuff from them by the case to use in some piece of equipment or another. Of course, they didn't have oil, so I had to get that at the parts store. Anyway, it's done now, so mark that one off the list. :D

bigvette1

A good quality like Valvoline 90wt lube is what ok. 2 quarts is what the rear holds. This is from a rear end reuilding shop. However, they said STICK WITH THE GM POSI LUBE.