2004 Corolla sludge on oil cap

I'll been hearing about sludge build up in some Toyota vehicles when I noticed sludge on the oil fill cap when I changed the oil in my 2004 Corolla 1.8L.
It has 66K miles on it and appears to run fine but it bothers me to know that there's sludge in the engine. Is there a procedure or an additive that removes the sludge? I bought the car used and I'm not sure how often the oil was changed. Will using 5-20 synthetic oil(Mobile 1) help disolve or flush out the sludge?

Thanks again,

Astroman

Rislone and Gunk and probably others make an engine flush that can help. Just poor it in your oil, let it run 5 minutes, then drain and change your oil. May take a couple applications. Only way to make sure it's gone is to remove the valve cover and have a look. Synthetic oil should drastically slow sludge buildup if not eliminate it. Not sure if you have a PCV valve ( Camry, RAV4 guy) but if so change it and clean any hoses associated with crankcase ventilation. Cheers.

Thanks RIP.

I'll give it a try and check out the PCV and hoses.

95Astroman