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Old 07-08-2010, 09:59 AM
 
Location: Earth
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When a car says "premium fuel recommended" is that the same "premium" according to the gas pump, the most expensive, 93 octane if I'm not mistaken? Or does "mid-grade" fuel at 90 or 91 octane suffice?

I understand that running the cheap stuff through when "premium" is recommended does make a difference. But actual premium gas costs about as much as diesel.
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Old 07-08-2010, 10:08 AM
 
8,778 posts, read 16,752,398 times
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Read this article:
Regular or Premium? - Feature/Features/Classic Cars/High Performance/Hot Lists/Reviews/Car and Driver - Car And Driver (http://www.caranddriver.com/reviews/hot_lists/high_performance/features_classic_cars/regular_or_premium_feature/%28page%29/1 - broken link)

.......and ignore the mopes that will come on here telling you you're going to blow up your engine if you don't exclusively use 93 octane.


LOL. I see the parade didn't take long to begin.
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Old 07-08-2010, 10:09 AM
 
Location: Purgatory (A.K.A. Dallas, Texas)
5,010 posts, read 13,171,292 times
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93.

Typically in luxury cars, you can use the cheaper stuff, but it ends up costing more in mileage losses. Also, if you can afford a luxury car, why cheap out on something that costs an extra $10 a month when the manufacturer recommends it?
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Old 07-08-2010, 10:10 AM
 
51,859 posts, read 41,758,040 times
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Quote:
Originally Posted by Eastern Roamer View Post
When a car says "premium fuel recommended" is that the same "premium" according to the gas pump, the most expensive, 93 octane if I'm not mistaken? Or does "mid-grade" fuel at 90 or 91 octane suffice?

I understand that running the cheap stuff through when "premium" is recommended does make a difference. But actual premium gas costs about as much as diesel.
I would think 91octane would be fine.

Around me you rarely see options different from 87, 89 or 91.

If you can get 93 then fine but 91 isn't going to kill it. I once spaced out and put 4 gallons of 87 in mine, caught my mistake so the tank was roughly 1/4 87 and 3/4 91 and I didn't notice any difference.
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Old 07-08-2010, 10:27 AM
 
Location: Pomona
1,955 posts, read 9,527,597 times
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My "weekend" car has a turbo, and premium fuel is recommended.

87 octane can work, albeit with diminished performance and mileage. Repeated the experiment 3 different times ... 87 octane yielded around 2 mpg (1.9, 2.1, 2.2 to be exact) LESS than running 91 octane. Discount 91 octane averaged 0.5 mpg less than top-tier gasoline. Doing the math, there was zero savings for me running 87 octane, and minimal savings with the discount 91.

Additionally, 92 octane up in Oregon yielded 4 mpg MORE than the watered-down (oxygenated) 91 in California.

YMMV, of course. The only way to know is to try it out and keep track of the mileage.
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Old 07-08-2010, 10:38 AM
 
Location: Planet Eaarth
8,955 posts, read 17,691,388 times
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Regular Versus Premium Gasoline

The Straight Dope: What's the difference between premium and regular gas?
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Old 07-08-2010, 10:39 AM
 
Location: U.S.A.
3,305 posts, read 9,515,598 times
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Premium is 93

Octane requirements are based on the compression ratio of the engine. Run lower octane and you will feel it. MPG will also suffer. If it asks for premium there is a reason for it.
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Old 07-08-2010, 10:58 AM
 
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Cars don't blanketly state "premium", they list an octane rating as well. For most vehicles sold in the U.S. the "premium" recommendation usually corresponds to 91 octane as that is the highest octane rating available in many states. For optimal performance and MPG, you should run the recommend octane grade of fuel as a minimum. If you don't, the car will still run, but with diminished performance. It is also true that putting in an octane higher than what is recommended will yield no benefit as the engine is not tuned to take advantage of the higher octane fuel.

The only caveat I would give this rule is if you are buying lower quality gasoline. Gas companies are rated in Tiers. Tier I is the highest quality gasoline you can get. These standards were developed jointly between GM, Toyota, BMW, Honda and several fuel companies. A couple common examples of Tier I are Shell and Chevron. If you buy lower quality fuel even if it is of the recommended octane rating it may still not provide optimal performance. In that case, I would recommend buying the highest octane rating available (generally 93). This is especially important for turbo cars and high compression N/A engines that can be very sensitive to octane and fuel quality.

Before people tell me I'm wrong, this information comes from many years in the transportation industry as well as my own experience modifying, tuning and racing cars.
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Old 07-08-2010, 11:03 AM
 
8,468 posts, read 13,641,437 times
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Quote:
Originally Posted by Stratford, Ct. Resident View Post
Read this article:
Regular or Premium? - Feature/Features/Classic Cars/High Performance/Hot Lists/Reviews/Car and Driver - Car And Driver (http://www.caranddriver.com/reviews/hot_lists/high_performance/features_classic_cars/regular_or_premium_feature/%28page%29/1 - broken link)

.......and ignore the mopes that will come on here telling you you're going to blow up your engine if you don't exclusively use 93 octane.
Be careful what you read. I have a relative who has a Lexus RX. It recommends that he put premium gas in it. After a while, he decided it wasn't necessary and started running it on regular. Within a few months, he had a clogged fuel pump and an expensive repair bill. Now he's back to premium and hasn't had any problems. Not everything's a conspiracy to rip you off.
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Old 07-08-2010, 11:10 AM
 
8,778 posts, read 16,752,398 times
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Quote:
Originally Posted by DennyCrane View Post
Be careful what you read. I have a relative who has a Lexus RX. It recommends that he put premium gas in it. After a while, he decided it wasn't necessary and started running it on regular. Within a few months, he had a clogged fuel pump and an expensive repair bill. Now he's back to premium and hasn't had any problems. Not everything's a conspiracy to rip you off.
I never said to run regular exclusively, nor did the article that i linked. The whole point is to realize that in many areas, super is rated at 93 while the manufacturer only requires 91 or 89 octane when they designate "premium" fuel only. Using straight 93(for ~99% of vehicles) doesn't benefit performance at all, and only adds further to big oil's profit line.
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