1999 Pontiac Montana cooling system problems

At 28,000 miles, the general tires that came w/the vehicle were completely bald & had to be replaced. They were supposed to be 80,000 mile tires & had been rotated numerous times, the cooling system: while on vacation, the cooling system overheated. Told by dealer out of town that radiator cap loose & was tightened. 3 weeks later low coolant light kept coming on & took to dealer on 8/12/00. Told coolant system dirty & needed to be flushed; $100.00.

I've experienced the well known (thousands affected) intake gasket leak on gm's 3.4l engine. At 75k miles, experienced low coolant, topped off, but no puddles. At next oil change, found oil to be milky-brown and reek of coolant. Dealer service confirmed intake gasket leak and repaired at cost of $700 including fouled oxygen sensor. Pontiac "customer service" was no help and was somewhat evasive when I asked if she had been involved with any other intake gasket problems.