3 Speed trans oil 90W?

[mrdave03]

I'm told I should run plain old 90w gear oil in my recently rebuilt 3 speed on the tree non synchro trans. I can't find it anywhere. The guy who sold me the trans said never use a GL5 in it nor a synthetic. Anybody know what would work or if 90w is available. I checked most auto parts here in northwest New Jersey to no avail...

[crhyno]

I last found this at my local West Marine. It is closed now but I know they are still open elsewhere. Good Luck.

[hotrod66]

i used 80/90 gear oil from Orileys auto parts. worked fine when i had mine rebuilt it is still in there 3 years later and no trouble and i drive mine like i stole it.

[Wrenchbender Ret]

80/90 is the replacement for 90 weight. There is nothing wrong with using GL5 in that type trans.

[66Submarine]

From what I've read the straight 90W will shift better/quicker. GL-5 is supposed to generally be somewhat corrosive to the brass parts in the trans. You can get straight 90W at Napa. (about to try some in my SM420...)

[WhippinSaw]

Sta-lube makes a gl-4 gear oil, Sold at napa, gl-4 is reccomended in the service manual. not sure whats the difference is but I used it just to be safe after I read gl-5 could attack brass parts.
http://www.napaonline.com/Catalog/Ca...229_0006410049

[mrdave03]

Thanks! Yes I had read about GL5 being corrosive to brass as well. I did find the CRC Sta-Lube 80W-90 GL4 at Napa so to be safe I'll be running it.

[66Submarine]

FWIW, I just changed the oil in my SM420 to the straight 90 GL-1 that NAPA sells (part number "NHF 65201"--says 65-201 on container). Initial impressions are that it certainly seems to shift quicker with the GL-1. And it's "cheap" @ $13 a gallon, too. Works for me!