With gas prices at alarming highs lately, those of us who tend to spring for Premium out of a vague sense that it’s better for your car might be second-guessing themselves a bit. A PEMCO poll found that 24% of respondents didn’t have any real idea what should go in their tanks. Here, PEMCO breaks down the difference between tiers of gasoline and tells you where to find the intel on what’s really best for your vehicle.

Of all the measures of inflation that show up in daily life, gas prices are probably the most glaring. Whether you fill up weekly or monthly, you’ll likely notice a difference in price each time you visit the pump. And if you’ve been filling up with Premium out of habit, this may be the time to consider whether the price really pays off for your car.

The short answer: Probably not.

About 76% of us say we opt for Regular because it’s the cheapest. But 24% also admit they have no real idea if that’s what should go in their tanks, according to a PEMCO Poll.

Contrary to what many people think, the real difference between Regular and Premium isn’t quality or additives. It’s octane. Premium fuel has higher octane, which means it’s less likely to ignite too early in the combustion process and cause your engine to knock (damaging it over time).

For certain older and high-performance cars, premium is better. And that’s spelled out in their owner’s manuals. Premium fuel also may make sense if you’ll be towing a trailer or, for some reason, need maximum acceleration. However, most newer cars run fine on Regular, because their ignition systems can compensate for varying octane levels.

If your owner’s manual says Premium is “recommended” but not “required,” it’s OK to experiment and see if you can detect a difference in mileage or performance when you burn one fuel or the other. If you hear engine knocking when you try out Regular instead of Premium, you’ll want to switch back.

Fuel additives may matter more for the health of your car than octane. If it’s in your fuel budget, consider opting for TOP TIER™ gasoline, according to Consumer Reports (scroll to the bottom of the CR link to watch the video). That’s fuel with more engine-cleaning detergents than the EPA requires, and some manufacturers including Honda, Toyota and GM say it improves performance and lowers emissions. You can find it at most big-name stations, often advertised right on the pump.

Regardless of the type of fuel you use, you can save money when you follow these super-saving tips to stretch your gas mileage from the pemco.com Blog.

Source: PEMCO