I just got a new car (as I’ve mentioned here) a couple of weeks ago: a Hyundai Elantra GT. (I cannot put into words how much I love this car, but that is not the topic.) I may have seen this topic addressed before, but rather than get in on an old thread, I figured I’d just get to my question:
Should I use “Regular” (87 octane), “Plus” (89), or “Super” (93)? In my past cars, I always used Super, and have done so in the first two tankfuls I’ve used in the new car. My first car was an '84 Dodge Shelby Charger, and the one time I didn’t use Super, the car stalled out and I was stranded. This is why I got into the habit of always buying Super with that car and with the ‘88 Daytona. Of course, those cars’ engine technologies were years inferior to what I’m driving now, so I really am unsure if there will be any similar repurcussions if I use Regular now.
When I asked the dealer, I got “You can use regular or super.” Yes, I say, but what do you recommend? “Oh, either is fine.” I don’t want it to be just “fine”; I want what will help the car work its best. The manual pretty much says the same thing: “Use 87 octane or higher.” Well, duh. I don’t think I’ve ever seen anything lower. My dad swears by Super and won’t use any other. Others say that Super actually robs you of gas mileage. (By the way, I use Mobil; I don’t know if that makes any difference as far as additives, detergents, and other goodies.)
Well, my simple question has now run several paragraphs, but I figured that some of the above info might be needed for anyone who knows this stuff to answer. So–what should I use to help my car run right and avoid problems?
It is better for your car to put a higher octane gas in it. It burns cleaner. I always use a high octane gas and at times I put an octane booster in. as for stalling out when using a lower octane, you really shouldnt have you might have had some bad gas or watery gas.
Sorry I can’t give a straight answer, but I have heard a number of theories: A mechanic I know swears that you should fill your tank with the highest octane available. As evidence he offers a story about a friend of his who worked at a small town airport. This friend filled the mechanic’s 15-year-old car with a mixture of high-octane airplane fuel and 97-octane “normal” fuel. Said car, according to the mechanic, “drove like no other four-cylinder junker” he’d ever owned. It got great mileage and performed outstandingly. After the tank was emptied, the effect ended. There’s also a gas station near an area racetrack that specializes in 100+ octanes (for the weekend racers who converge there) and said mechanic has been known to go out of his way to fuel up there. According to him, high-octane fuel is the very least you can do for yr car. He’s had about twenty years experience working on automobiles and isn’t known for flights of fancy, so I tend to trust him…
That said, many experts vehemently argue that you must follow the octane recommendations as written in your owner’s manual. Anything more or less - according to them - will either hurt your engine in the long run or waste your money in the short run. Of course, it’s always a good idea to consult your owner’s manual for ALL questions! And if it says 87 octane is good enough for your car, is it worth the extra ducats to second guess them?
Basically, the best that experts seem to offer is exactly what your salesman said, “either normal or high octane.” Still, consult yr owner’s manual (I sleep with mine under my pillow, so I can extract more information through brain-osmosis) and keep paying attention to how yr vehicle responds to its environment (which it sounds like you do a good job of already!)
Hmm. Well, like I said, even the manual was a bit vague, saying “87 or higher.” I wish they had just said “use 87, dummy.” I think I will try the 87 and see how it goes. I don’t think I had what that article refers to as “high compression,” so 87 will likely be fine. Thanks.
And for nearly all cars that aren’t performance cars, and I think that includes your Elantra, you should use Regular 87 octane gas.
Higher octane actually means that it contains less energy, octane is a measure of a gas’ ability to resist premature combustion. This allows car manufactures to use higher compression in the combustion chamber, which in turn allows the engine to produce more power.
Most cars are designed to run on the cheapest available gas, and high octane gas can damage them. This occurs because the high octane doesn’t fully burn in the cylinder and ends up burning in the exhaust manifold or somewhere else downstream.
If your car is knocking or pinging, this means you have premature detonation. In this case, higher octane will prevent the problem. If you don’t have this problem, use the lowest octane available which is what most owner’s manuals recommend.
Very high octane, such as racing fuel, is designed to work in high compression engines. It most definately can hurt your normal car. All gasolines have the same level of detergents and burn equally cleanly.
Do a search on this forum. This question comes up about once every 3 months.
The manual for my 1999 Jeep Cherokee says to use 87 octane unless it knocks. I haven’t read it in a while, but it might say that if the engine knocks with 87, have it checked out.
Avgas comes in three flavours: 80 octane, 100 octane and 100LL (“low lead”) octane. Eighty octane seems to be pretty scarce, as engines built in the last 20 years or so (unlike car manufacturers, airplane manufacturers don’t build their own engines) are designed to use 100 octane fuel. Older engines designed for 80 octane run fine on 100 octane.
Avgas contains lead. IIRC “low lead” 100 octane fuel contains more lead than leaded mogas (automotive fuel), so using avgas in cars and motorcycles probably isn’t a good idea. Also, avgas and mogas are formulated differently. The former is designed for use in Lycomings and Continentals which tend to run at a steady RPM, and the latter is designed for engines whose speeds vary from a few hundred to a few thousand RPM. Using avgas in a ground vehicle is not recommended. They each contain some additives and lack others based on the intended use of the fuel.
Nineiron wishes to suggest that handy read the previous two times in this thread where I already stated that I had read the manual and its advice was vague at best.
Very few engines require 93 octaine. Like Corvettes, and that funky supercharged Nissan Frontier I saw yesterday. Most get by fine on 87 like every else here stated.
nineiron, Imust need glasses. But a neat thingyou can do is try edmunds.com, find your car, find the forum & ask or read what other guys with your car use.
What everyone else said. Use the octane recommended by the manual, and stick with it. Make sure when you bring it in for maintenance (and presumably “tuning”), you stick with that octane.
Higher octane is required for higher compression engines (10:1 ratios and thereabouts) to keep it from igniting before the spark under the heat induced by higher compression.
Using high octane in an engine designed and/or tuned for lower octane will damage the engine over time.