Four-stroke engines that run upside down, i.e. many racing motorcycles and airplane engines, use what is called a dry sump. The sump is a seperate tank where the oil is collected.

Two cycle engines are pretty much on the way out because of the pollution. Calif. has basically banned these engines, esp. in lawn mowers. Most outboards are going to 4-cycle. OMC (Evenrude, etc.) went bankrupt a few years ago and it looked like the end of the 2-cycle ob engine but since Bombard of Canada bought them out it looks like the 2-cycle will continue. Many city and state reservoir will not allow 2-cycle engines to operate on them.

I have worked with large (5,000 to 40,000 hp) marine engines for the past 25 years and most that I have seen are 2-cycle. The reason being that they do not require a gear box. The are started in forward or reverse using 300 psi starting air and a sequencing valve. They run at from 40 to 80 rpm. Most all new ships and many older turbine ships (Queen Mary was converted in Hamburg) use high speed marine Diesels. They are greatly more efficient than turbines and require much less maintenance that a turbine/ boiler combination.