I have had an oil leak since I bought this Prado with 170000km on the clock three years ago. I didn't bother to check it as the leak was minor. When I did check it out a few weeks ago I found half the threads from the cam cover bolts had been stripped. I tapped the stripped 6mm threads to 7mm and replaced with 7mm bolts. It is running smoothly now without any sign of oil leaking.