Originally Posted By: exranger06
Back when I drove my mom's 94 Explorer, I would always keep it in D instead of OD (would only use the first 3 gears and not shift into overdrive), unless I was going on the highway, in which case I shifted into OD as I was climbing the on-ramp. I had read using D uses a stronger part of the transmission or something and it helped the trans last longer. My mom now does the same thing. We must've done something right, as that trans has almost 220k miles on it and never had a problem with it. I never bothered doing that in any other vehicle though.
If I'm towing or carrying something really heavy in my truck, I'll turn the OD off.
Forgot to mention, when I drive my Accord to my in-laws house, I'll downshift to 2 as I'm ascending their driveway. Otherwise it tries to shift to up to 3rd gear, then downshifts right back to 2nd as I round a corner. It's easier to just lock it into 2nd.