So pretty much the way I came upon this was that I looked everywhere to find what kind of gearbox oil to add into my 5-speed z28. I came across a manual and it said in wright on one of the pages...here some piks and hopefully this helps some of you guys out there that are having the same problem as me....







and this is the manual that it from..


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Even tho they copy a lot of their info from the factory sevice manuals, I would rather trust the factory service manual from HELM, INC.

 

Yup, pretty familiar stuff... I think everybody on here has that book and has seen that. As well as, of course, those of us that have the service info published by GM themselves, via their licensed publisher for service info, Helm Inc.

The factory waffled back and forth over what to put in there from year to year, depending I guess on whether the Gas Mileage Dept or the Warranty Expense Dept won that year's Big Kahuna Award at the spring Golf Scramble Outing.

Fact of the matter is, the parts themselves were identical in every way, right down to every individual part #, from the introduction of the T-5 through 87; and then, from 88 up.

So, you tell me: what difference does it make which fluid those same parts get bathed in? Are you going to believe, with a straight face, that the wrinkles in the sheet metal or the available sticker packages for any given year, affect those parts and that fluid somehow?

Bottom line pretty much is, put a non-volatile petroleum-based lubricant product in it. ANY such product will do, and has satisfied the warranty at one time or another.

In the couple dozen of those weenie POSs that I tore up before an alternative became available, I tried basically evey fluid known to man (and woman as well). I finally had the best luck with a mix of half-and-half ATF and 75W-90 Mobil 1. Didn't keep the trans alive any longer than anything else; didn't not leak out the stretched-out front countergear bearing hole any slower; and sure smelled worse than most other things. But it shifted the slickest with that combo.

 

After being a factory technician for many years and seeing the ATF come out of my T-5, I'm gonna have to take a pass on the non-factory Chilton information provided.

 

I've always used this.