Don't mean to get away from engine oil, but similarly, I pulled the gearbox inspection cover last week to check if still had some oil and found some patches of rust on a couple of bits (plenty of oil), so that's last weeks job for later today or tomorrow hopefully....I've a bit of slop in the kicker shaft bush, so 'water-from-the -sky' (doesn't happen often) may have run down that when I was at work, parked on side-stand.
I have *dared* to give it a wash at the ride-in engine-wash place a couple of times, but try and avoid that bit, but I used a 10mm length of SS tube in between the kick-lever and the case, is a good snug fit over that bush, but not on any of the other spare ones (must be oversize). Plan is to stick a couple of 1/16" section 'O' rings inside on the shaft when I get some....should keep oil in and water out (a bit)