I bought a 2000 Honda Accord with 108K miles. I don't think the previous owner kept up with fuild changes. Engine goes thru oil @ 1qt per 500 miles. I have been all over the engine and can find no evidence of leaks. Plugs are normal. No smoke of any kind in exhaust. No oil in distributor or coolant. The only thing I can think of is varnished and seized piston oil control rings. Any ideas?