Originally Posted By: Robenstein
Yeah call me old fashioned but running at 3,000 rpm on the highway I would think it would be a bit harder on the oil than if I was on 55mph backroads at 2,300 rpm. If I was doing the backroads instead of the interstate, I would be more comfy at 10k oci. I will do 7500 miles and get the oil analyzed.
To play devil's advocate, you probably negate those 700 rpm's just by the fuel dilution backroads could cause -- getting off the throttle, then on it, then brakes around a curve, then hard throttle, etc. Steady rpm's on the highway, if reasonable, are likely to be the easiest the oil sees.
Although, a car that is running 3k at highway speed (unless you're driving 90+) probably doesn't need to be driven that hard anyway or isn't geared right. I dunno...