Motor oil comes in a variety of forms, designated by pairs of numbers, but the most common two are 10W-30 and 10W-40. What's ...

Over the past 40-plus years, I have changed the oil in more engines than I can begin to count. If you're about to change the oil in your car yourself, consult the owner's manual that came with ...

An oil’s impact on fuel economy could range from 0.5% to 4% depending upon ... For instance, a 5W-40 flows quicker through the engine in cold temperatures because of the 5W.

Synthetic oil used to be something only performance cars needed, but not anymore. Now it’s the manufacturer-recommended engine lubricant in many mainstream vehicles, such as the Subaru Forester ...