i just changed the starter on my 300 was some rust on gears is oil supposed to be in there i have never changed or added oil here

 

I wouldn’t worry about it, oil mist is supposed to get round the gears when the oil gets hot enough but the 300 is a cold runner, many don’t even have a fan, and if you mostly do short runs in cold weather the oil won’t get hot enough. I do lots of 300 starters and many have “mayonnaise” under that cover for the starter gears, some have the outrigger bearing in the removable cover badly worn, probably from lack of lubrication. Squirt some oil round the gears and bearing when you put them back.