I'm currently taking apart my ST162's engine, and I'm wondering if there is a common (or near) common fault of leaking oil up near the intake manifold. I have the head off and I can't see much wrong with it, and the intake manifold seems alright as well. There has been a fair bit of back pressure in the oil system causing the car to breathe a bit of oil back up the inlet system. However, it has actually been leaking oil from near the top of the engine etc and I'm just wondering if there is any kind of common problem with a seal or something like that in the Celica ST162. I know this question is pretty vague but it's worth a shot anyway.
Guess what it turned out to be? A rear main seal - of all things - the driveshafts tend to make finding an oil leak kind of tricky cause the oil tends to get flung anywhere and everywhere!
Other common issue is the distributors o-ring - which is fairly high up there too. Aside from that you've got your camshaft seals - which don't often cause problems but it pays to check some of these things. It's really a case of the usual suspects. In the end I replaced every seal in the engine anyway - and then some