Hi, i just recently purchased a 1998 STS. (new to cadillacs, always been a grand prix/ bonneville guy (3800 series 2). So i have a few quick questions. First on the oil change, the northstar in the sts holds 7.5 quarts correct? Next, a few times i got a random overheating. Just driving and the gauge spiked. Pull over, turn on heat, and goes back to normal. Any ideas, i was thinking of starting with a thermostat.

 

Yes, 7.5 qt.s, Thermostat is a good place to start.