I have a customer that has a 1985 Buick 3.8, and an 89 Oldsmobile with a 3.8. Each car has been overfilled (with a total of 5 quarts) since I have been servicing his car. His low mileage car has 260,000 miles on it. The high miler has over 340,000 miles. He is... Login to read more.