I have a 5HP sears pressure washer with briggs and stratton engine that is
leaking oil. This engine has no oil filter or oil drain plug. To change oil
I tilt it on its side to drain the oil out and put new oil back in that
filer hole, so it's not like there's a loose plug or filter.
Furthermore I can't really tell where the oil is leaking from. There is oil
all around the engine and it leaks very slowly -- a few drops per day.

I wonder if this is a blown head gasket. If it is, how hard it is to repair
it myself, or how much would it cost to have it repaired?

I see several options:
-try to replace the gasket
-put new and thick oil in before each use (twice each year). Previously I
use synthetic 10w40 left over from car oil change.
-buy a new washer

Any advice?