before you replace the crank seal, replace the pcv valve. Lexus/Toyota are notorious for excess crankcase pressure causing oil leaks. the is likely the original pcv valve from when the engine was built.
This is for [overbys] About two weeks ago me and a friend of mine. We did a brake job on my 1996 Toyota Avalon XLS. Front and back. We noticed after we took the tire off the front passenger side and started to replace the pads. We had noticed it was leaking small amounts of oil. Just came from my repair shop several houres ago. They told me that the crankcase seal is going bad. They said nothing about troubles about lexus/toyotas problems with excess crankcase pressure. For fairness i will say maybe they did not know about thoses problems. I am going to check my pcv to see if it is good or not. If it is bad i am/hope that is the problem.