1991 Pontiac Bonneville Q&A
1991 Pontiac Bonneville Question: film build up under radiator cap?
I would flush the cooling system and possible remove the thermostat while flushing the system and replace the thermostat and radiator cap and antifreeze when servicing the cooling system When using a cooling system flush product like Prestone cooling system flush I like to flush the system out well and add a few table spoons of baking soda afterward to ensure acids have been fully neutralized. - patrick mannion
DON'T KNOW. WHAT TO DO - Visitor