Hello, Yes, there can be something wrong with the distributor o-ring which causes it to leak. Of course, there can be any other number of causes as well. Best of luck! CarGrrl
I would get an entire upper and lower oil gasket kit(s), the Felpro one is about $25 for each kit, and just go through the entire system, after 150,000 miles these 4 cyl. and 6cyl. Toyotas leak oil from a variety of places, the biggest offender being around the crankshaft at the belt side of the motor in the area behind the timing belt (you may have to pull the motor to solve the main oil seal leaks), so find a good affordable mechanic in the country who gives you an honest quote or do it yourself.
... the oil pump o-ring, & don't forget that thin spaghetti like one, are big offenders for leaks in Toyota Celica's 2200 & 1600 engines, you might as well do the front crankshaft seal too whilst the timing cover is off, the whole timing cover seal kit costs only six dollars (note it's more laborious to do these engines than the old style 22RE series, but hey that's life with front wheel drive / horizontally opposed placement), and you'll need a helper to hold the cover back on from the top while you tighten it back, some sealant as well.