Vardar

Hello there...

I always wondered if I use 89 octane instead of 93, what would happen, will it hurt the engine, if yes how?

Can someone explain please? How does quality or grade of fuel effect the engine?


Thank you in advance.

ohlord

have a high compression,high performance engine.High test fuel is needed to provide the level of knock resistance the engine needs to run at that high compression.The ECU will compensate for some level of pinging or knock under some load values,it can not adjust for the lack of octane in the lower regular fuel.It in the long term will hurt your engine and will reduce your performance.
ohlord

E55 PWR

if you own an AMG, you MUST run premium, simple as that

Vardar

I realize that. I was just curious why. I never used 87 0r 89 octane before, even when I drove 98 Cherokee years ago..

Jons95c36amg

Sunoco used to have ultra 94oct. Now premium is 93. My c36 likes BP brand.

steve s

it may not have been the best if the cherokee demanded only 87. higher octane resists knock. high compression and induction forced engines may have higher potential of detonation. this is when the compressed gas and air mixture spontaneously ignites before the spark plug ignites. this is especially true in high load situations or when the ambient temperature is high, such as during the summer months. higher octanes reduce this potential. but by doing so, it also reduces the combustability of the mixture, making it harder to ignite. yada yada i think that is the gist of it. if ur enigne required only regular 87 octane, then adding 93 would probably have decreased its mileage, even if it is a mini difference.

ECTurboGSX

As was stated before, octane resists combustion. As temperatures and pressures increase dramatically during the combustion process, the fuel may ignite prior to the spark ignition. This is especially prevalent in engines with high compression ratios or forced induction. If you use lower octane fuel, your mixture may pre-ignite and when you are dealing with pressures in excess of 160 psi and temperatures over 1600 *F, big explosions that happen before they are supposed to is a bad thing.

Vardar

Thank you very much for all the useful information. You answered my questions clearly.