I have just under 391K miles on my accord. I only add a qt per 5-6k miles but my valve cover gasket is leaking pretty bad and needs to be replaced.....I am sure mine is an external leak because there is a tiny drip on the distibutor side of the cover. about 100K miles ago I was really worried because consumption was high---but when i switched over to PYB and PP followed by M1, things slowed down----when i say high, i mean 1qt per 3K miles....now I am paranoid, but it is pretty low now