I couldn't find a post that seemed to relate to this issue... I'm working on a friends 1981 280e which has been plagued with oil leaks. After replacing everything but the rear main seal the car is still leaking but through some holes in the aluminum head and I'm not sure what they would be for. There are four of them that are visible from underneath the car, about .25" diameter each, and they are located in the head just slightly below the exhaust manifold. It seems they might be intended as a sort of warning... "your valve guides are going..." something along those lines. Any advice would be helpful!