I just bought a 2000 Corolla with 56K miles on it. At least that's what the odometer showed. After 1700 interstate miles the oil showed 2 qts low. I drove that trip at 70--75 m.p.h. at 85--90 degrees, rolling hills and over Appalachian Mountains, with air conditioning on. The day before I left I had the oil changed. Havoline 10W-30. When I freaked at being 2 qts low the oil change guy said, no way he made a mistake like that. The Toyota Owner's Manual talks about higher oil consumption at high speeds. But of course it won't name numbers. Is this normal? After adding 2 qts to the full point I checked 1 week later and the level shows 1/2 qt low for mainly highway miles at 55 to 60 mph. I SEE NO SMOKE FROM THE TAILPIPE. No oil leaks on driveway. No oil has been thrown out (no oily engine parts). Is this something that I will have to live with? ALSO: did my running that engine 2 qts low during that trip brutalize the engine and shorten its life? I'm thinking about going to Mobile One. 57K miles now. Lots of questions here, but when I bought this car I though I had a trouble free car for 1/4 million miles. P.S. I baby this machine.