I was changing oil in wife's Lexus GS350 yesterday and noticed small amounts of oil at various places on passenger side of engine. I had been topping off her oil about 1/4 quart every 3 weeks for past few months. I can't see a lot from under or above car but pretty sure this is not a valve cover leak. I understand the engine in this particular car is subject to timing chain cover leaks and the motor has to be removed to replace the gasket. Anyone had any experience with this?