C-1 Posi fluid

[Jerry C.]

What is the best mixture of fluids to put in a rebuilt posi unit? Thanks in advance

[Mike M.]

Re: C-1 Posi fluid

a 4 oz bottle of "quell" by piedmont chem co, dayton ohio 45475-0904(contains spermeciti ) and mobil synthetic gear oil works for me. mike

[Duke W.]

Re: C-1 Posi fluid

Any SAE 80W-90 GL-5 gear oil is fine for the mild temperatures that most vintage Corvettes are driven in. Brand name is not important. Like engine oil, choose based on SAE viscosity and API specification.

With Positraction you need at least one four-ounce bottle of friction modifier, which is available from GM and other sources for the typical driving and weather conditions.

Back when your car was built, the friction modifier contained whale oil (as did Type A Suffix A ATF), and thus got the moniker "whale sperm". At the time whale oil was the best known addtive to prevent wet clutch chatter.

Whale oil products were oulawed in the seventies in the US, so the industry came up with a synthetic friction modifier that replaced the whale oil.

It's probably just as well because animal oils usually deteriorate more rapidly at elevated temperatures than synthetics.

Leave the axle housing slightly underfull with one bottle of the additive. If you detect clutch chatter, add another 2 to 4 oz. If not fill to the bottom of the plug hole (hot) with gear oil.

Duke