Premium vs. regular gas

I am looking at buying a used Volvo (2002 s60) and some of the specs say it only takes premium gas. All of the Volvo owners I’ve talked to say they just use regular unleaded though. Will it make a difference or cause car problems if I just use regular? I am not looking for high performance or anything, I just don’t want to screw up the car over time. If it does make a difference, then is there a way to tell whether the previous owner always used premium or not?


You asked, and Cecil answered.

Thanks! I did a search on the boards but didn’t think to search for the master’s answer!

Note that in most gas stations there is “the pump in the middle” and that is a good compromise on cars where Premium is Suggested but not Required.

My wife and I have had BMW sedans and they are listed as needing premium gas. The manual was not kidding. Gas stations have made a few mistakes a few times over the years. It is immediately obvious and it feels like the engine has shifted into save itself mode. BMW’s will run like that to some degree but their electronics switch to a very low performance mode that does not feel healthy.

My suggestion would be to fill it with premium and drive it until it is nearly empty. Put a partial amount of regular in it to give it a test drive. If it feels the same, you should be Ok to use it. It you feel a difference, fill the rest of the tank with premium and stick with it.

I just got a Nissan Altima, which recommends premium. When I asked about this, I got the same story as Shagnasty’s: the engine will compensate when running on regular grade, to avoid knocking, but it will not perform as well and will likely get noticeably worse gas mileage.

I’m too skittish to try it out though.

::: Scratches head:::
An S60 requiring premium? Not that I recall.
Which flavor S60 are you looking at? The base car, the 2.4T or the T5?
Which spec, published by whom?
To the best of my recollection, none of these cars require premium. I typically ran my company cars on mid-grade due to the fact I did not have to pay for it, and I thought I could detect a slight running difference. Also on cheap regular, I could detect a sulfur smell from the cat converter.
Now that I have to pay from my own gas, I run straight regular in my 05 V70 base car with no issues.
I tell you what, I will be happy to research this on Monday when I get back to work and let you know.
If you ave any other S60 questions feel free to ask.

Don’t these cars specify a octane number or do they just say “premium”?

The only car I’ve ever owned that had to be run on Unleaded 96 (“Premium Unleaded”) was a 1976 Chrysler Galant. I’m frankly surprised it ran on Unleaded at all, but that’s what it was designed for, and if you put Unleaded 91 in it the engine would knock, you’d have significantly less power, and the fuel efficiency was, frankly, shit, even by the standards of a 1976 car. 96 Octane ran beautifully, though, and if you put 100 octane speedboat fuel in it (I knew a guy who knew a guy who raced motorboats)… Well, good times, good times. :slight_smile:

The only vehicles I know of nowadays that require 96 or 98 Octane fuel to run properly are HSV and FPV cars, owned by people that really don’t care about the fact it’s $1.85 a litre to fill their V8 HSV with 98 Octane fuel every time they take it out…

Premium octane changes depending on your altitude. It’s different in the high mountain areas of the west then it is in the rest of the country.

Not just premium. Regular unleaded is different, too. It was 86 r2/m all through Colorado and Wyoming last time I pass through there. I’m used to it being 87 everywhere else.

I note that I have a Thunderbird Supercoupe which has a supercharged engine requiring premium unleaded. It has an octane plug in the engine compartment that can be pulled if you need to run regular. It retards the timing a bit. I don’t know how much it would hurt fuel economy and performance as I never ran regular unleaded unless I had the supercharger belt off. Really, I don’t know what the point of the plug was since the car had a knock sensor. I guess there was a limit to how much it could dynamically adapt.

It’s all 85 here in the Denver area. 87 would be “midgrade.”

You guys are getting ripped off- fuel in Australia and NZ is 91 Octane (Standard), 96 Octane (Premium) or 98 Octane (Ultimate/Optimum). 85-87 Octane? That’s a bit close to Kerosene for my liking. :wink:


And I believe the Brits and Yurpeans laugh at Australian octane ratings.

And their fuel costs twice what ours does, so I still think we’re getting a better deal out of it anyway. :smiley:

And they don’t have FALCON UTES. :smiley:

No, we’re not. There’s two things going on here.

The first is that at high altitude, there’s less air available, so the relative compression in the cylinder is less. Since octane is the resistance to preignition, a lower rating is needed at higher altitudes.

The second is that in the US, an average of both the RON (research octane number) and MON (motor octane number) is cited on the pump. Since most countries use RON exclusively, your numbers would be the equivalent of about 87, 91, and 93.

Keep in mind that a higher octane does no good if your car isn’t designed for it. I’ve heard it can actually give -less- fuel economy if your compression isn’t high enough, because the fuel may not fully combust. I’m not sure if I trust that completely, but I do think the difference in a lot of cases is purely psychological.

ETA: The quote was taken from TM’s cite.

I went over to Car Talk to see what Tom and Ray’s take on the issue was. They pretty much say go ahead an use regular unless you’re bothered by the pinging/performance issues. Here’s a link to their discussion: Tom and Ray’s Humble Opinion on Premium vs Regular

I bought a Mazda 3 with the 2.3 engine–without realizing that it wants 91 octane. It seems to run okay on regular, but there is a difference in acceleration. I prefer for the car to GO when I hit the gas pedal, so I stick with the expensive stuff.