I did the oil pump, chain/guides ,cam and lifters at 400k miles as maintenance. Now at 526K miles. Crazy thing is the car has the original injectors and still gets 46 average MPGs while being driven hard.
I have over 450000
I replaced the oil pump and chain plus cam and lifters as preventative maintenance last timing belt job. I change the oil at 15k intervals and the engine looked very clean inside. No burning oil or leaks.