Fall is a good time to change oil and filters. Check your owner’s manual for the rating and viscosity, but most cars nowadays use an SJ-service rated oil. This rating is some measure of the oil’s longevity and resistance to oxidation and evaporation. SJ oil is fine for older engines that specify an SG- or SH-rated oil, because the rating always improves when a new one is introduced. The SAE viscosity rating is a measure of how thick the oil is. All modern cars should use a multigrade oil, probably a 5W-30 or 10W-30. The W in these ratings stands for a winter viscosity. A multigrade oil will be as thin as the thinner (5W- or 10W- rating) when the engine is first started. This will allow oil to flow more rapidly and lubricate parts that have had all the oil drain off of them overnight. A thicker oil might not be pumped to remote parts of the engine rapidly enough. On the other hand, a thicker oil (the second number in the rating) will resist becoming too thin when the engine reaches operating temperature. The American Petroleum Institute is an industry watchdog and oils bearing the API emblem can be expected to meet their specifications.In spite of what your brother-in-law the shade-tree mechanic tells you, don’t use a heavier grade of oil just because you used to in your older car. Modern cars were engineered to use 5W-30 or 10W-30 oil year-round. Check the owner’s manual to be sure. The lighter oils are also better on fuel consumption and can significantly improve mileage. News source: Men MSN