[ctesla]

soobie,
Stealthee is right again.
while old school batteries are ok (and affordable) as most all people still use them,
AGMs and Gel cells are superior for hot and especially cold weather..
Absorbed Glass Mat batteries cost more; however, they also can last potentially 1-3 yrs
longer in a vehicle (3-5 yrs in a solar home), so this outweighs cost hike..
also, they have the woven mat material inside; as opposed to a lead plate, so
temperatures do not affect them, they do not leak the sulpheric acid if cracked, and
they do not vent harmful chemical vapors; which is why racers love them, as they can mount in trunk, farther away from engine, yet will hold a 100% charge after six plus months with no sulfation, and a higher amp/hour (and usually reserve capacity) ratings, at extreme high or low temps; and 15 times more resistant to vibration (colorado roads anyone)..
i have been using Gates Optima batteries off south broadway since '91; until the rubber company closed their doors, and then i will buy optima or interstate (whichever amazon has on sale); and then rotate my car battery into a solar/wind project (as i've had some optimas last for 15yrs)..
they are definitely worth the money; if you can afford..
and just FYI, autozone (and sometimes others) have a policy:
WITTDTJR (wit-uh-jer)
what it takes to do the job right; and will offer free battery changes, with purchase..
walmart i think is about $7-10..
hope this helps..