No, it wont wear out the motor, that what they are supposed to do. Most 4 and 6 bangers turn 3000 rpm or more on the highway anyway.
You can go 60 mph at 1000 rpm? Wow, thats low. Are you sure? I would guess at least 1400 rpm or higher.
I dont think i would compare cruising at low rpm to the same as idleing. Theres no laod on the motor at idle, although i guess the lower the rpms, the lower potential for wear, but I dont think it really would be hard on the engine cruising at 3K. Higher rpm wear occurs when you racing, and winding up to 500-6000 rpm.
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1993 GT/AOD
'93 Mustang GT