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Manual Transmission Oil

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Lyle View Drop Down

Joined: Jul/17/2014
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lyle Quote  Post ReplyReply Direct Link To This Post Posted: Dec/09/2017 at 10:57pm
Here is a link to a chart but the page does not give all the information on oil formulations and reasons for the engineering behind them:
A magnet is a good thing, crankcase or gearbox.
I should add that some engine oil detergents collect moisture to reduce acid build up from combustion gas blow by. In engine oil this is good as it is changed frequently.
A gearbox does not see these gasses and the detergents can accumulate with the moisture below the oil. Unless the gearbox gets above the temperature for moisture separation it will remain mixed with the detergent. This is not a good lubricant and can corrode gearbox components.  
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tomj View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Dec/10/2017 at 11:30pm
i think we are all over-analyzing this, but though i fear adding to it, a transmission is nothing like and engine. the oil doesnt get stressed much at all, there's no combustion byproducts to condense, etc. i've never measured it (the only way to really know) but in my experience i've never felt a truly hot manual transmission. hot would be > 250F, and modest motor oils are good for far more than that.

all that said, after messing with motor oils i ended up with plain old 85w90 or whatever it was. did not have the bronze-eating crud, i forget the brand.

prolly changing trans fluid every decade, even with the wrong oil, would be overkill. even the bronze-eating phosphorous takes a long time to act. 

the last two transmissions i built i stuck a piece of super-magnet just below the trough that collects oil thrown off the rotating gears, so oil flows past it, to catch any steel dust or whatever. only had one of them apart after, it had some inky black but it was completely un-feelable. another piece in the hole in th end of the drain plug. on both nothing on it other than the india ink like black.

1961 roadster american
195.6 OHV, modded
T5z, 3.42:1 mustang axle
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