Hi, I open the oil cap of a diesel engine after starting it, in just a seconds, my hands was somehow sprayed with oil spots.
What will I expect to see? No oil should be coming out? Or mist of oil or oil spurting out?
Thanks

You should leave the oil cap in place on any and every engine while it is running.

Yes, it's normal for oil to at the opening. That is why there is a cap there.

For what reason would you remove it?

Agreed, Rich. That crankcase is like a hurricane of large, heavy, steel and iron pieces flailing around at 150 mph. Expect random droplets of oil.

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Originally Posted by CaptainRich

You should leave the oil cap in place on any and every engine while it is running.

Yes, it's normal for oil to at the opening. That is why there is a cap there.

For what reason would you remove it?

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Just checking, as others say that when oil is spurting out, there is a problem, like blow-by, in the engine, other says also that good engine should have only mist when opened while it is running.

I do know that there are many moving parts inside like rocker-arms, pumps that circulate oil and so oil may come out when it is opened, but what/or how much is expected?

curtis73 is a bit melodramatic but yes you will get oil chucking out the filler pipe opening when the engine is running. Why not do a compression check if you are worried about the engine. Do you have blue smoke coming out the exhaust ?