"No Spam" > wrote in message
. com>

> My girlfriend has a 1995 Mercury Sable GS with Overdrive
Transmission.
>
> We don't use overdrive around town because we have both heard people
> say using it for town (stop and go) driving stresses it and to only
use
> it on the freeway and on long trips.
>
> I have also heard it is ok to use Overdrive around town.

It's perfectly fine to use Overdrive all the time, except sometimes
when going down long hills, and the people who advised against it have
obsolete information or owned one of the first Ford 4-speed automatic
overdrive transmissions, which would sometimes make the engine stall in
panic stops if in overdrive. If you don't use overdrive in highway
traffic, not only will your fuel economy be noticeably worse, but your
transmission torque converter may run hotter since its lock up clutch
remains disengaged (but some cars lock up this clutch even in lower
gears)

Avoid additives except possibly an occasional bottle of Dry Gas (to
remove water from the gas tank) or Techron (removes carbon from fuel
injectors, pistons, heads, and intake valves). Don't overdo them.