MADISON, Wis. -- One question that sometimes gets overlooked when people get their vehicle's oil changed is whether standard oil or synthetic oil is better.

Many "quick lube" oil change companies are pressure car owners to make the switch. But is the pressure because it's more expensive and the business makes more money, or is synthetic oil truly better for your vehicle?

Madison Area Technical College instructor Bob Gray explained the difference between standard, natural oil and man-made, synthetic oil.

"Synthetic is an engineered oil," Gray said. "The product can even be an organic compound, like soybeans, canola. Or it can be a plastic resin."

More and more credible shops, like Zimbrick Motors, are switching to a synthetic blend as their standard, WISC-TV reported.

And while there are many good things associated with synthetic, Gray said if you have an older car, synthetic is not for you.

"In my opinion, (for a) pre '95 with high miles -- like up around 100,000 miles -- I would definitely be very cautious about going to a synthetic oil," Gray said.

That's because the older technology and gaskets will cause synthetic oil to leak, and it doesn't have the lubrication for the old push-rod engines. Synthetic is also more expensive.

But there are some good things associated with synthetic. It lasts longer, meaning you don't have to change your oil as often, and some claim you get better gas mileage.

"The good thing about synthetic oil is you can run (it) roughly three times the drain interval as the petroleum-based," Gray said. "So by doing that, it's going to cost you maybe less in the long run."

Gray said the best bet is to ask a mechanic you know and trust to see which engine oil is right for your vehicle.

People should also check their owner's manual. Many manufacturers, especially of newer cars, actually recommend synthetic oil, and the owner's manual will tell you that.