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What Gearbox Oil Do You Use?


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I have a Alpina 350cc M138. I have recently drained my gearbox oil. I have the Hugh's Manual and it specifies to use SAE 90. I was wondering what you use and recommend? Also, I am using SAE 30 for clutch oil, good?

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I had a number of Sherpas (near identical engine to alpina) 250 and 350 from 1975 to 1980.

I used to use SAE 90 or 75-90 gear oil in the gearbox and 10w-30 universal tractor oil in the clutch. Never had any problems apart from occasional clutch slippage on start up in very cold weather.


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As the Bul has an seperated containment for the gearbox I use SAE 90 (EPX) with API GL5 specification, which is also been used for differential gearboxes.

advantage: can manage real high pressure loading

downside: works really smooth first when warmed up by the engine in winter, not for use with clutch!

ATF for primary is perfect

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I use SAE 80W90 transmission oil (API GL5). Should be better for colder conditions.

Sae 90 or 80W90 also reduces the noise level from the gearbox a bit better than the thinner 10W40 or other multigrade Motorcycle oil.

For the clutch I use GRO Gear Extreme 75W, which is a light full synthetic transmission oil.

It made the clutch in my Cota 4RT very smooth with almost no drag, even when cold, so it should be fine for my Sherpa which has modern friction material on the clutch plates.

Edited by guys
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