I've had 20w-50 oil in the gearbox, over the course of a week around half leaks out of the sproket side.

I'm going to buy some 90w oil, which it is supposed to have, but should I be thinking about taking the box to bits and checking replacing the felt and steel washers, or even consider a sealed bearing?

Is 90w oil really that much thicker than 20w-50?

Also, I used the same oil in the engine, would monograde 50w be thicker (I'm hoping it will stop a few leaks here too).

Thanks,

Andy

email (option): Adh325@hotmail.com

Hi Andy..Original oil grades for both engine and gearbox were sae 40 with 50 in the engine in hot weather. The solution to the gearbox problem is to fit a sealed bearing on the drive end, removing the inner seal prior to fitting. More generally, clean and deburred gasket faces, new gaskets and modern sealants such as silicone are the answer to controlling leaks.
Also check the operation of the crankcase breather to ensure it is venting crankcase pressure correctly...Ian

email (option): ian@wright52.plus.com

Thanks Ian, is replacing just this seal difficult? Must everything in the gearbox come apart?

email (option): Adh325@hotmail.com

It's a complete gearbox strip down unfortunately...Ian

email (option): ian@wright52.plus.com