As an update, I tried switching to a synthetic oil to see if there would be a change. Nope. oil was 1/2 quart low after 150ish miles! I just got done pulling the 1st, 3rd, and 4th plugs (w/o removing tank or air filter, could not reach the 2nd) 1st and 4th looked good... the 3rd, well.. see for...