Are the benefits of high-octane gasoline worth the price?

When it comes to cars and driving, I prefer practicality over style any day. I drive a Saturn wagon, which is not remotely likely to turn any admiring heads, and the manner in which I conduct my vehicle as I wend my way down the avenue is slow (read: at the speed limit) and careful (read: boring).

As I wish my vehicle to last for as long as possible, I try to maintain it to the best of my ability (which is, admittedly, not saying much). Along with regular fluid and filter changes, I am in the habit of selecting high-octane gasoline during the fortnightly fueling ritual.

My question is this: are the benefits I gain by filling my tank with supreme unleaded worth the extra money I am paying? Again, I am not a performance driver, and my car is a 6-cylindar station wagon. Am I doing something good for my car, or wasting money?

We’ve been down this road before (at a stately 55 mph, of course!):

The car talk guys even said that it’s actually kinda bad to use higher octane on some engines because it burns hotter, which could cause damage over time.

IIRC, it isn’t that it burns hotter, but that higher octane is more resistant to burning than lower octane gas. Thus, the combustion timing is off, and burning gasses may be expelled out of the cylinders and there will be flames in the exhaust manifold, where there isn’t supposed to be flames.

Thanks for the responses so far. Looks like I’ll be saving some money from now on.

So if high-octane gas is doing my car little good, and even potentially bad for it, is it more beneficial to go with the mid-grade or the regular unleaded? Does it make a difference to drivers like me, other than in terms of price?

Read the manual. It probably recommends regular (87 octane) unleaded. As long as your engine isn’t knocking, it’s fine.

My car, and many others, sense the octane of your fuel and tweak the engine (timimg, etc) to match. Result: higher octane = more power. There aren’t many cars, afaik, which require high octane. As mentioned, check your owners manual.
And I take the “car talk guys” with a grain of salt. They tend to be bombastic, and lean toward saying that which gets you to nod your head.

This really goes for all aspects of your car. Manufacturers spend a lot of money researching this stuff. You can’t even say “planned obsolence,” because there’s more value in your car being regarded as long-lasting than forcing people to buy new ones every three years (there are better ways to do that!).

So, brand of oil, natural or synthetic, oil change frequencies, tune-ups, and all of that stuff can be found in your owners’ manual or maintenance manual (if the latter comes separately, like mine).

As a further benefit of getting to know your owners’ manual, you can’t be convinced to do stupid, unecessary services at dealers or shops or even quick-lube places. You know, you go for a $30 oil change, and get talked into a $125 transmission flush with only 60,000 miles on your car? Or rotate the tires every 5,000 miles?

My point is, trust your owners’ manual.

Another Saturn ower here.

When my car was a few months old, the check engine light came on. The dealer said the diagnostic code was “sluggish O2 response.” They said this is generally caused by using gas with too high octane. Most likely, I hit the 89 or 91 octane button on the pump by mistake when filling up. They recommended immediately filling up again with 87 to dilute any remaining high octane fuel. The car ran fine and there seemed to be no damage.

I have only seen two types of cars that require it:

  1. High performance luxury cars (my friend’s BMW Z4 fro example)
  2. My Ford Focus SVT. It is a small, relativelt inexpensive car that has a good bit of power for its size and has been heavily modified from the standard Focus for performance. I highly reccomend it for enjoyable driving on a smaller budget (though it has what I consider a less than attractive look).

The general rule is to use the lowest octane gas where your car won’t knock and ping. For cars that are in tune, it will be whatever the manufacturer recommends. For all Saturns it’s 87.

If your car is out of tune you might need 89 or 93 to prevent pinging. If that is the case, use the higher octane gas until you can fix your car.

My informal research suggests this is rather common - a sort of “If it costs more it must surely be better” approach. As the responses thus far indicate, this rarely holds any water.

Do they measure octanes differently in US than in Europe? Because in Europe the smallest octane number you can find is 95 and the highest 100.

Your general point is well taken, but these are poor examples. Many cars on the road today have a recommended transmission service interval of 30,000 miles. For some front-wheel drive cars tire rotation at 5,000 miles may be appropriate.

Yes, they do measure octanes differently in the US vs Europe. Europe uses RON and US uses MON, which produce different numbers. I may have gotten that backwards.

Here’s a good FAQ about octane

Yes, a different measurement is used. From here:
"In the United States, pump octane is an average of 2 ratings, research octane (RON) and motor octane (MON)…Research Octane number is always higher than Motor Octane number…In Europe, they only report the RON.

Related question…in this area of the country, 89 octane has 10% ethanol, and so it is normally 2-5 cents cheaper per gallon than the 87 octane stuff. I have been using that for years, but is there any disadvantage to doing so?


You’re right – I hope eveyone follows my advice and reads their service instructions, and don’t look at my examples and say, “hey, Balthisar said I don’t need no stinkin’ transmission service!”

(Examples from my personal experiences with my own service frequencies, although I usually fall for the tire rotation thing, since it’s “only” $3.00 extra at the dealer).

I have a Saturn wagon, too (a '97), and I had always been using the mid-grade stuff, 89 octane, because that’s what the owner’s manual says to use. Since gas prices have been skyrocketing last spring, I started been using regular, and it’s been fine. My husband commented that he had no idea I’d been using the mid-grade all these years, and that I should have been using regular.