Probably the biggest controversy surrounds the use of synthetic oil. Let me state unequivocally that synthetic oils are the best thing to happen to the internal combustion engine since the introduction of the cam-operated intake valve. Synthetics provide great protection, extend the change interval, and in some cases even free up a little horsepower and increase your mileage. Hell, for all I know they might even help whiten your teeth and freshen your breath, but as usual there’s a catch. Synthetic oil is expensive. If you’re using it to extend your change interval, something that I find perfectly acceptable, than the cost is offset by the reduced need to change the oil. But if you’re switching over to a synthetic and still plan to change the oil every 2,000 miles, then frankly, unless there is some other compelling reason to use the stuff, you’re wasting your money.