NOS GM posi additive?
 

I have a box of NOS GM posi additive, is this the good earlier stuff with the whale oil in it?? 1970’s vintage?

Thanks

Check the box, may be a date code on it. The number looks too new to me, just a guess, to be the "good" oil...

I have the same box of posi. additive i received from my neighbor who passed away a while back that was a Chevy mechanic. Can't find any date on the box. Wonder if the additives are still good, i would think they are??

They stopped using Whale oil in lubricants back in 1974 so if they do have Whale oil in them, they have to be before then. That's when we saw all the internal transmission oil coolers in radiators fail causing all the intermixing of Antifreeze and ATF and pink milk shakes and blown transmissions.
I believe they should be just fine. I also had a neighbor give me a case of 20w50 Royal Purple Racing oil from cleaning out his Parent's garage in Berwyn Il 5 years ago (That was supposed to be 35 / 40 years old) and I sent a sample to a lab and had an oil analysis done on it. They said it was 100% okay and had not seen a concentration of Zinc like that in a long time. I say use it

Bill

I was the trans tech in a Chev-Caddy dealership during that period, no fun cleaning that gook out of trans internals but very lucrative!! - Bill W