I'm leaving the rear timing belt covers off. Do I have to put a bolt in this hole (the top one in the picture) as well to ensure oil doesn't leak?



I think there was 1 or 2 bolt holes behind the camshaft spocket as well which I already put back in.

no, not the top, but yes the bottom one. the top hole gets a bolt when you install the front cover, but it doesnt leak anyway