Pulled my oil screen yesterday - first time in 17 years!

Yeah, there was about a 1/4 inch of sludge in the ratainer, but big deal for 17 years.

Wiped out most of the sludge & did my usuall thing - which is to hose down the thing with brake cleaner. Only problem was, it also removed the finish from the outside of the retainer plate. Inside finish is a perfect satin black, unaffected by the brake cleaner!!!!

Sanded the outside down, prepped, primed & refinished with Rustoleum satin black & reinstalled.

But, I got to thinking (yeah, dangerous). Why is the interior surface impervious to harsh chemicals? What kind of paint was used, and, assuming the exerior was painted with the same material, what was it?
Pat

I've noticed the same thing on most engines I have torn down. But I've got no good explination. Realistically, the inside doesn't even need paint, since the oil will protect the metal.

Mark,

After careful cleaning of th inside, I've determines that it isn't painted - it's anodized! Explains a lot, especially when it's subjected to the harshness of sludge that collects in it. But, that's the inside.

So, since most everything underneath seem to be finished in satin, that's what I did to the outside. Though, it seems to look a little too glossy to suit me - drying right now, or I'd send my usual bad pics. May cool down to sattin when itdries. Used Krylon.
Pat