> "tflfb" <fuksatw@qwest.net> wrote in message
> news:xDEtc.2$p%6.8514@news.uswest.net...
> Do you waite till your battery fails or replace it when you figure its
> about to.

Why wait until it fails? You'll likely wind up getting stranded somewhere.
However, replacing it too early before it's really due to be replaced isn't
cost effective either. A simple solution is to determine the CCA (cold
cranking amps) remaining in the battery. Many shops have a small hand held
device which hooks up to the battery and measures the reserve capacity. I
recently replaced my 410 CCA Interstate battery as it had gotten down to
about 225 CCA and was noticeably cranking the engine slower especially when
the car had sat for a day without being driven. I don't know what to make
of the "four year" rule that was mentioned. My battery took eight years to
get to the point where I replaced it though your mileage my vary.

Eric