Blowing Oil

This is a 1992 Wrangler with 45,000 origional miles. It just started blowing oil out around the oil filler cap. A thimble full a day is a rough guess and it just started doing this about 2 months ago when cold weather hit. I switched to 5W-30 oil but no help.

I checked the crankcase vent to the airfilter box and the continous vent to the manifold, both are open. Also, the filler cap gasket looks fine, it is a hard plastic gasket that is not really an airtight seal.

It is making a real mess on my garage floor and the engine is caked with filth because of it.

Any ideas????

i have a 92 and had an oil leak that i couldn't find until i looked at the oil sending unit for the oil gauge. i replaced it and had no more oil leak.