I have minor oil leaking which is creating fume smell periodically inside car.

Can I try tightening cover bolts without damaging anything ?

 

Hi there. I have done this on my 93 Protege, so this might be some help:

You can try tightening the valve cover bolts, but do not overtighten! (Max about 50 in-lbs). The valve cover gasket is usually a high temp rubber material that sits in a recess in the valve cover itself. Overtightening will actually make things worse by pinching some areas of the gasket and allowing others to bulge.
It may be better to remove the the gasket and inspect it for pinch marks. if it has any, replace it with a with a new one. Remember if you remove the gasket to add some high temp silicone gasket sealant to the recess that holds the gasket in the valve cover. Otherwise it will still leak!

Cheers.

 

the valve cover gasket costs about $20 and takes 6-8 bolts to replace. don't re-tighten them. just bite the bullet on the $20 and spend your next 30 minutes fixing the issue the right way.