I agree buy the 87 and save. The higher octanes do nothing for our engines. If you really wanted you could go to Walmart and pick up some STP Octane boost and that to the tank and save some cash. Not much but every little bit counts.
It drives me crazy that on the pumps it says "best performance" on premium (91). It's nothing of the sort.
They should be fined for misleading advertising.
Octane has no relationship to the energy content of the fuel, only it's resistance to ignite, and ironically the higher number means it's "more" resistant to ignite. Typically in cars that require 91 octane the engine is higher performance, but the fuel is not. So, running a higher octane level than your engine needs will not give you more power or mpg.
I think the confusion comes from the fact the opposite is true. Running a lower octane than the engine is designed for can decrease your power and mpg, but the reason for that is the engine itself is designed for higher performance (typically compression). Lower octane burns more easily, and in a higher performance engine that means it can ignite before it was supposed to, commonly called knock. When that happens, the knock sensor in most modern cars will retard the timing to compensate, and in retarding the timing, it does tend to decrease power and fuel efficiency.
So going with a higher octane than your engine was designed for does nothing, but going with a lower octane than your engine was designed for will hurt power and fuel economy. (and tends to be hard on the engine.) I think it's that fact that confuses people.
yes the BSFC will go up as the ethanol content increases, but the overall flame front speed, engine power, and thermal efficiency go up (to a point). In effect it would seem a small amount of ethanol e10 or 20 in an engine made for 87 should get better mileage than putting 91 or 93 "pure" gasoline in it just a thought.
Hey everyone. I had a 2009 Nissan Sentra 2.0 base model. And I used 91-93 octane fuel for when i drove it. Then after awhile to save some money. I got some 87 octane for my car and it ran rougher and there was a ticking sound..
But can anyway explain to me why the sentra ran rougher when i put recommend 87 octane?
Oh yeah I traded in my sentra for the cube ;D ;D ;D ;D ;D ;D ;D