My Forester XT wants 91 octane, which is not difficult here in Canada where most stations sell 87, 89, and 91. Sunoco's the exception I know of with something weird for its four grades.
I was in the US last month and most stations were 87, 89, and 93. So I put in 93. Was that the right decision? Sunoco had 87, 89, 91 and
93 (I think) so I used 91. It was only 2c/gal cheaper than 93, so if there wasn't a convenient Sunoco I just used 93 from someone else.
How come 91 is so hard to find? And what do American XT owners do, put in 93? Should I look for something higher than 91 myself when I'm at home?
91 (R+M)/2 octane isn't hard to find in California. It's the standard octane rating for premium here. A few years back, 92 octane was the usual standard for name brand premium here.
If you seek out 93 when your car calls for 91, your probably wasting money.
That's what I figured, thanks. I'll keep using 91 at home.
What does Subaru recommend in the US? I had to hunt for a Sunoco station to find 91 octane (there may be others, but the Exxons and Mobils etc. didn't offer it). I assume 93 won't hurt, except for the extra 2c/gal.
I'm in New York, and I can't find 91 except from Sunoco, so I just put
93 in most of the time. At these lower altitudes, better to run the higher octane. Another alternative is to run a tank of 93 down to half and then top up with 89, but that's a pain.
I have the same problem here in the Northeastern US. My truck runs best on 91, but nobody sells it. I usually use the next grade up. Luckily,
93 is only ~$0.10/gal more than 89, so it's not that big of a deal.
The truck runs like crap under load and acceleration with our state's 87 & 89 octane blends, and the manual recommends 91+, so all those who are about to post and tell me I don't need it can save it. =8^)
If it's only 2c/gal difference, I'd just got for the higher rated fuel and not worry about it. You certainly won't hurt the car.
Advantages: if it's hot, you have to carry heavy loads and/or do a lot of hill climbing, there's less likelihood of pinging at a given spark advance point. However, your ECU will do the adjustments automatically, so you'll probably never even know anything's different. Some might argue you'll get better mileage and/or power, but again, unless you've got a REALLY sensitive backside, I doubt you'll feel it.
Disadvantages: it costs more. Out here in SoCal the differential's generally 10c/gal/grade (89 costs 10c more than 87, 91 costs 10c more than 89) so those who talk of wasting money going over grade have more solid ground to stand on with their arguments. However, if it's only
2c/gal, and assuming you spend more time at home in Canada than down in the States, I'd not get too worried!
It WOULD be interesting to see if there are any fuel economy differences between fuels on either side of the border if you keep close tabs of such. My Subie's never shown any real difference from one grade to another, my Camry V-6 book says I'll get more power jumping a grade, but my records show NO increase in fuel economy, and I can't feel anything. Guess this is where YMMV really proves itself?
It won't. If you check your owner's manual, it probably says "91 AKI minimum". There is a slight difference in fuel economy south of the border since they use different additives in the gas than we do in Canada.
Different additives. 93 is very expensive to make in Canada since the additives the Americans use is not allowed up here. So it doesn't cost very much more to make 93 than it does to make 91 in the US. And, people will generally buy more of a higher octane fuel even though it doesn't do anything unless the car is tuned to use it; like forced-induction cars.
About the only unmodded US Subaru I've heard of that requires 93 (R+M)/2 octane is the Impreza WRX STi. Some exotic cars may be equipped to deal with higher octane fuel.
The strangest thing I've heard of are local 76 stations selling
100 (R+M)/2 octane unleaded racing fuel at about $5/gallon (likely more these days). It's dyed blue, and its nickname is "Smurf Gas". This article mentions something about using this stuff in a 2001 Ferrari 550M Maranello, although they didn't detect a difference:
Apparently it blends fairly linearly with premium unleaded. Some places have it at the pump, while other wholesalers only sell the stuff in large cans.
I don't know if it's really about "additives" per se. It's all about the distillation process and the proportion of higher octane hydrocarbons that ends up in the final product. There isn't going to be anything in 93 octane unleaded that isn't in 91 octane fuel.
The stuff I mentioned is unleaded and meets all state and federal standards for reformulated gasoline. 100LL wouldn't be street legal and might kill a catalytic converter.
Sorry. 100LL is dyed blue and I assumed they must be the same thing. I'm surprised you can get an unleaded 100 octane, else the gov would make aircraft burn it.
Up here the difference is about 10c-11c Canadian between 87 and 91. In Ottawa the big sign is typically only for 87 but if it says "88.4" I would expect 91 to be 98 or 99c (per L).
I don't have the receipts handy, but after being annoyed at paying a premium for 93 at various stations on my drive to PHL, when I finally hit a Sunoco and seeing 91, I recall it being only 2c/gal difference. I'll check when I can, it may have been 2c/L or about 8c/gal.
Thanks everyone for the advice! On this next trip I'll buy 91 at Sunoco when I can, but won't make any detours looking for it.
One thing that bugs me about premium gas is that it costs a tiny bit extra to make, but the profits are so much bigger. I'm glad my 2000 Legacy L drinks the cheap stuff.
There's an interesting article in the recent issue of Car and Driver magazine. It makes a good case for name-brand gas. And it says we'll soon get a legal indication of which gasolines meet the highest standards of quality.
I don't think the 76 100 octane gas is any kind of traditionally distilled fuel. One of the places selling it mention that it's made of "essentially pure components". It sounds like they're blending relatively pure hydrocarbons. Apparently this stuff burns faster and is more volatile than normal gasoline. I've heard that some types of high octane racing fuels burn faster, which is counterintuitive. Most people seem to associate "higher octane" with "slower burning".
Apparently 100 octane is the most you can get that's street legal. All the higher octane unleaded doesn't seem to meet reformulated gas standards or maybe don't have the additive package needed.
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