Q. I have two questions. On my 2006 Pontiac G6, how are you supposed to do a tire rotation? I heard you bring the front tires straight back to the rear, and cross the back tires to the front. I thought you bring the front tires straight back and bring the rear tires straight to the front without crisscrossing. Which is the right way?
My second question is when do I have to change the timing belt? Is it at 60,000 miles or can I wait to do it after 60,000 miles?
A. For rear-wheel and four-wheel drive vehicles, the tires should go back to front and the fronts should cross going to the back. On a front-wheel drive vehicle, like your G6, you will cross the rears going to the front and take the fronts straight to the back.
Your G6 has a 3.5 engine in it, which has a timing chain and not a timing belt. There is no maintenance schedule on a timing chain. For cars with a timing belt, there are some with a 60,000-mile interval but most require a timing belt change at 90K or 105K.
Q. I have several cars, one I use as my daily driver throughout the year, and a number of collector vehicles that see limited use during the nice half of the year. The daily car gets its oil changed every 3,000 miles year round. But on the collector cars, it can take two or three years to put 3,000 miles on them. I have heard both that clean oil is clean oil no matter how long it takes to rack up the miles, and that even oil that sees minimal use should be changed every year regardless. What are your thoughts on this?
A. I agree you probably will not put enough miles on the cars to dirty the oil, but it will still have the various byproducts of combustion in the oil. Therefore, I would recommend you change it once per year. Now the question is when should you change it, in the fall before putting the cars away or in the spring before using them for the summer?
Assuming the cars are kept dry and inside, I would recommend you perform your oil change in the fall before storage so you do not store the car with any acidic contaminants in the crankcase. If you can do this without starting the engine again, that would be best. Your oil will be clean and good to go for the summer driving season.
Q. Sometimes when I drive, I hear a rattle from under the car. Is my muffler going bad?
A. It is hard to say what this noise could be without listening to it, but it sounds like you may be describing a loose or rusted heat shield on the exhaust.
These are tin shields that shroud the exhaust and when they get loose, they cause a light rattle that may sound like a ticking noise. This noise may trigger at certain rpm's and under specific load conditions.
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