Ditto.

However, I wouldn't put oil in the cylinder. This would result in a higher reading, unless of course you need oil to turn the engine over, then why would you test it anyway. To see what I mean, try it both ways on the same engine. If there is no change in compression, and your sure the cylinder was dry before hand, then the engine is no good. The engine is worn enough so that the viscosity of the oil will not seal off the wear. Not sure if I worded that correctly. Anyway you get my point.

All non-RC engines are tested without oil, even two cycle outboard engines and motorcycles. If someone puts oil in the cylinder(s), before testing, of something you are going to buy, they are trying to put one over on you.

Perry