Out of curiosity, does the longevity of my car's engine increase or decrease when O/D is OFF during city driving? I thought I read somewhere that turning O/D off decreases the wear and tear factor in stop and go traffic.

 

If you are driving below 45 mph, then I would shut it off so the tranny doesn't keep shifting in and out of O/D. Plus, you don't want to lug the engine around at a low rpm at that speed... Otherwise, keep it on.