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With gas prices where they are now, it's probably actually more economical to run premium. Premium gas seems to cost 20 cents more per gallon around here, regardless of the price of regular, $2 or $4, premium is 20 cents more - that's roughly 5% more money at $4. Most cars will get more than 5% better mileage on premium (assuming they are set up to use it).
If you wanted minimum cost per mile, just to get from A to B - I think you have the wrong car.
How much are you spending per month on gas anyway? Would a 5% reduction in this cost really do anything for your bottom line? Just sayin'.
Technically your Dad is correct to say "running regular won't damage (hurt) the car", it has a knock sensor so it will retard the spark enough to avoid detonation. If you are stuck with nothing but regular available, you can use it and it won't damage the car, but you won't save any money by doing so.
Most cars will get no better mileage on premium. Premium is for high compression engines. It does nothing to benefit lower compression engines. It does not provide better mileage. You may get worse mileage if you have a high compression engine and use unstable gasoline (lower octane), but "most cars' do not have high compression engines. I see no differnece in mileage if i use non-premium gas (lower octane), but I have only done so two or three times when premium was not available.
Many people believe that higher octane gas burns hotter, or cleaner or provides more power. It does not. It is simply more stable and allows greater compression without pre-ignition.
You are assuming that there is actually a difference between premium and regular gas. My comment was based on the possibility that there may be no difference. If the gas is all the same, then no car gets better mileage or any other benefit from premium. Not even high compression cars.
I spend about $1500 to $2000 a month on gas, but not just for my car. I have no idea what the usage is per vehicle. Mine is the only one that requires premium gas. Last night premium was 26 cents higher. It varies, sometimes it is less than 20 cents sometimes it is 35 cents more. The gap seems to be widening the last few days as gas prices come down. At 35 cents difference I am probably looking at $600 to $800 per year difference. That is lot to be throwing away if there really is nto difference.
While I am happy to trade performance for lightly higher costs, I am not interested in throwing money away. Not too long ago I probably would not have really cared if i might be wasting $800 a year for nothing. However things are different now and I have a lot of important things that $800 could go to. (College tuition for kids, car repair, pay down credit card debt, bring our charity donations back up closer to 2008 levels, etc).
1 there is more bang for the buck in regular. 2 Regular will start a cold engine in cold weather better.
Octane ratings are based on compression ratios. Around 10.5:1 is where high test starts to be a concern.
It is well known that the EPA wants fuel mix overly lean, and so car manufactors comply, and then ask you run High Test to compensate for overly lean mixes.
Run the lowest octane your engine will burn, and not ping.
Im sure this has been asked before but, does it really matter what gas you use in your car? My car manual says to use Supreme but my dad says it wont hurt it if i use regular gas.
CJ, you forgot what I put in the parens - "assuming your car is set up to use it" - which the OP's car is. You are of course right that an engine originally designed for regular will *usually* run as well or better on regular (and since regular has a higher BTU content per gallon, usually you get better MPG with regular anyway) (although, I have seen some higher mileage engines that were set up for regular but have built up enough carbon that they ping on regular, and will run better on mid-grade, particularly in summer.
The Acura in question will probably cost less per mile running on premium than on regular.
Older Detroit Iron cars with adjustable timing frequently will cost less per mile, even if originally designed for (leaded) regular, if set up with more ignition advance and run on premium.
There is indeed a difference between premium and regular.
Oh lord, how many times do we have to go over this?
If your car recommends premium, use it. If it doesn't, don't.
You can use a lower grade in a pinch; it won't hurt it, but it will be down on power and fuel economy. I suspect that's particularly true for a high-strung engine like the one found in an RSX-S. Nice car, by the way.
It also has a EGR system that will add burnt gas exhaust to the engine cylinders that will act to slow the burn rate which is what high octane does.slow the burn rate.
Oh lord, how many times do we have to go over this?
If your car recommends premium, use it. If it doesn't, don't.
You can use a lower grade in a pinch; it won't hurt it, but it will be down on power and fuel economy. I suspect that's particularly true for a high-strung engine like the one found in an RSX-S. Nice car, by the way.
Agree on all points EXCEPT if the car doesn't have a knock sensor and requires premium gas. In that case there is no way to automatically adjust mixture and timing to compensate for lower octane, and damage may result from using lower octane gas.
Maybe someone can chime in and tell us what year knock sensors became standard.
Agree on all points EXCEPT if the car doesn't have a knock sensor and requires premium gas. In that case there is no way to automatically adjust mixture and timing to compensate for lower octane, and damage may result from using lower octane gas.
Maybe someone can chime in and tell us what year knock sensors became standard.
The OP has an Acura RSX. It has a knock sensor. It can pull timing.
The OP has an Acura RSX. It has a knock sensor. It can pull timing.
I'm aware it does. At some point all cars came with knock sensors, back in the 90's I think, and maybe someone knew when that would be.
My post wasn't specific to OP's car, but to provide info for someone doing a search on the topic.
Last edited by vmaxnc; 09-29-2011 at 06:06 AM..
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