Slickone
Senior Member
But you don't know that, unless you've done tests. What is the recommended octane for your car?I like knowing that I'm giving my car the best I can at any given moment, and that I'm meeting recommended octane. That way if anything goes wrong down the road, Honda can't blame it on me using inferior gas. =D
And Honda won't blame anything on you if you're using at least the required octane, regardless of the recommended octane.
Myths about premium gasoline
https://www.cartalk.com/content/premium-vs-regular-0
Using an octane higher than your car can use can actually lower performance and gas mileage. I'm not saying this applies to the civic, but don't assume. Higher octane burns slower. And some premium (depends on blending) can have less energy per unit volume than regular. And your car is putting unburned hydrocarbons in the air, and probably increasing carbon build up in your engine.
Octane rating is only a way to measure resistance to combustion, nothing more. If cylinder pressure increases from using a higher compression ratio (or higher temperature, timing changes to ignite at higher compression, etc.), you want to offset with more a fuel more resistant to combustion to prevent knock. If you don't increase compression, but raise resistance to combustion, obviously you're losing power. Also they increase the octane rating by adding ethanol.
https://coverhound.com/insurance-learning-center/is-high-octane-gas-better-for-your-car
"The U.S. Federal Trade Commission said that high-octane fuel will not clean your engine better than its lesser counterparts, and a Car and Driver test found that at least one car designed to run on regular actually lost power when filled up with high-octane premium."
http://time.com/money/4349724/premium-gas-v-regular-gas/
These "premium recommended" cars got the same MPG on regular as premium (and the same seat of the pants power).
http://fortune.com/2016/09/07/premium-gas-sales/
"The final route to raising octane is to blend in a higher percentage of ethanol, which has a very high octane rating, but contains less energy than other blending components so achieves fewer miles per gallon."
I've seen more than one test that use a few vehicles where some even lost HP and MPG when upping from 87 to the recommended octane (and of course, some gained). And yes, I know some here have seen higher MPG with higher octane (calculate if it's enough to overcome the cost difference).
The thing is there's no way to know what the highest octane your car will take advantage of actually is, unless you do before/after tests. It could be the "Recommended octane", or that recommendation could just be Honda at least giving you the rated HP, not wanting to tell you you could get even more power at higher octane, which could also effect sales of their higher up models with more rated HP.
Summary: Don't assume using higher than the recommended octane is best.
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