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Regular or Premium


I own two cars that require premium only (a BMW and an Acura). Both are late model (07 and 06). BMW is 6 cylinder and Acura is 4. Can I switch to regular without ruining my cars.

If you want to save money, get rid of both cars and buy Hondas or Toyotas. If you need to fuel up in an EMERGENCY, you can use regular, but don’t fill the tank all the way. Top up with premium as soon as you can.

Prolonged use of regular will defintiely ruin the engines of both cars.

The additonal cost of using premium is less than a dollar a day. Why bother risking expensive damage to your car for such a low pay back?

I have an old car made in 1978 that requires premium fuel. I get very irritated with people that drive newer cars that require premium fuel and then put regular in the tank. When I siphon gas out of cars that are supposed to use premium fuel and the owner has used regular gas, my cars knocks like a marble tournament.

As others have pointed out, using regular may ruin your engine. I really hate to see an engine destroyed over a few pennies a day for the extra cost for premium gasoline.

“When I siphon gas out of cars that are supposed to use premium fuel and the owner has used regular gas”…

Thanks for the laugh. I agree with your post.

The answer to your question is in the Owner’s Manual. it should tell you:

nothing use regular

Use premium use premium*

Recommends premium Use what you want, but if you use regular you will likely get a little less power and lower mileage.

You sure can! While you’re at it, ignore the oil change requirements. Every 50 thousand miles is just fine, and instead of buying that expensive motor oil just use Wesson. You can get a gallon of the stuff for like 9 bucks at the grocery!

You should stick with Premium. These cars are designed and tuned to use Premium. Using less octane than 91 can cause damage. You might get away with using regular, but you are risking expensive repairs to expensive machinery.

If you want to use regular pay attention to the octane requirements of the next cars you buy to replace the BMW and Acura. There are plenty of very nicely equipped cars, trucks, and SUVs that require only regular gas. In your list of priorities it would appear that use of regular gas is now higher on the list. Has prestige dropped down a few notches?

In the real world, few engines can tell the difference between 87 and 91 octane…Most modern engines adjust themselves to operate without spark knock even on regular gas…If you can not detect any audible detonation or spark knock, you will not “ruin” your engine. Destructive detonation can not happen without you knowing about it…

“I have an old car made in 1978 that requires premium fuel.” (Triedag)

I do not believe any car sold in the U.S. in 1978 required premium fuel…In 1978, there was only one grade of fuel available for new cars, “Regular Unleaded”…It was several years after that that “Premium Unleaded” was introduced, replacing the old 100 octane “Leaded Premium” on the pump island…

I hear a little bird singing, “cheap, cheap, cheap.”

"I own two cars that require premium only (a BMW and an Acura).

Why did you buy these cars if you weren’t willing to pay for the premium gasoline they require?

Yes, you can switch to regular, because you won’t keep the cars long enough for the damage to manifest itself. But I pity the poor suckers who buy your cars after you get rid of them, because they are going to have expensive problems.

This is why I won’t buy a used vehicle that requires premium fuel.


My Mazda says it recommends premium, despite it being a turbo charged engine. The price difference between 87 and 93 octane here is 20 cents. Sure I could save $2.50 per fill up if I went with regular(I fill up at 1/4 tank, so I usually get 11~13 gallons), but I haven’t even bothered to try to use 87 octane yet, and won’t, unless I’m in the middle of BFE and Bubba Jay’s gas station is the last station in 50 miles and only has 87 octane and I know I won’t be able to make it to the next station without stopping.

You bought premium vehicles, so pay the price, or switch to a Civic or Corolla

I’m sorry - I don’t understand why you would buy such expensive vehicles and then try to skimp on fuel…

Its like the fool I saw in a Ferrari filling up with regular at a Swifty station.


If the manual, instrument panel, or fuel door say “premium required” it means just that. You must use premium or risk expensive damage to the engine. You may get away with it, but odds are not in your favor with that gamble. If it says “premium recommended” it means the engine was designed to run on premium but will not suffer dire consequences if the owner chooses to save a couple dollars each fill-up by using regular. I don’t think that kind of savings will make sense if you end up with both of these luxury cars in the shop for new engines a few months later for using fuel that they were not designed to operate with. Frankly, I think something’s wrong if you have two $30k+ cars in the driveway, but are looking for a way to save a couple dollars each fill-up. If you don’t want to pay the extra 20 cents per gallon (that adds up to a whopping $2 per ten gallons of price difference between the two) when you fill up, don’t buy premium luxury cars, or if you do buy premium luxury cars, be sure to find out before you buy if they will run on the fuel you would like to buy for them.