Right, or wrong, we switched from the expensive Cat oil to Non Detergent straight 30 weight several years ago (I think I read about that on this forum???). I've had zero problems in my 1010's, 623's, or 3535's. It was just the other day that I noticed the "slight" clouding in the 3535's, hence the posting on this forum. I changed out the 3535's oil yesterday, with the Cat oil.....and we'll see. At no time did I ever have any external leaking, nor did I have an increase in crankcase fluid. Maybe a slight amount of internal condensation is enough to "not mix" with the ND 30W oil....which from what I read here....the Cat oil should alleviate.