Just returned home from my local GM dealer where I had the coolant changed. I was concerned because that service was never performed and it has been almost seven years. Tech said coolant was not that bad and the cost was $121.60. They vacuumed out the system which was really a non-intrusive way to remove the old coolant and draw in the new coolant. I am going to do it again next summer just to be sure I get all the old antifreeze out. Even though the car only has 42,000kms on it I am also going to do a complete tune up including plugs. I do not want the plugs to "freeze" in the aluminum heads.
I was worried about this service but am now a happy camper and pleased with my treatment at the Dealership. Regards, Moe