- Buick Ownership
- 1999 Park Ave Ultra; 1985 Olds Delta-88 Royale
Coolant temp on my 99 Ultra is not constant. On a cold day on the highway it never gets to 180. This morning (1°F) it was only 160 even after a 30 minute commute. If I idle for 10 minutes it'll drift up to just over 200. Is this just a thermostat problem?