Tohatsu MFS30B making oil?

I have a Tohatsu MFS30B That has 40 hours on the hourmeter. The other day I checked the oil level and it showed overfull by about 3 millimeters. As you are probably aware the fuel low pressure pump is mounted in the tappet cover. My question is, Is it possible or likely that the fuel pump is leaking petrol into the engine. The motor has been operating lately at lower throttle openings (high idle) could this be a factor. Thanks in advance.
Barry

That can happen, but seldom does. If and when a pump fails that way, it typically dumps a LOT of fuel into the crankcase, resulting in radically high oil levels in a very short time. Sniff the oil. If it reeks of gas, the pump could be leaking. You can pull the pump off (2 screws), keeping the fuel lines connected to it, and pressurize the fuel system with the primer bulb to see if any fuel drips out of the pushrod area of the pump. You can have your dealer address that under warranty.

More than likely, the oil itself and the fill level contributed to your situation. Run 10w-30 non-synthetic oil, with NMMA FC-W rating. Fill about 1/2 to 3/4 on the dipstick. All 4-stroke outboards of all brands will make some oil. This is exacerbated by extensive low-speed operation, and colder temperatures.

Thanks Paul for your reply. I reckon you are spot on with the diagnosis, I am used to 2-strokes which obviously don't have these problems.
Will try your suggestions. Merry Christmas from Australia.
Barry