One of chris fixes best vids was his youtube on octane...
Ever wonder what grade gasoline should you use in your car (what octane)? Are you paying for premium gas when you can just use regular? Are you using regular...
youtu.be
Have not heard of this tuber, I agree it is complete and excellent for levels of gas engine owners. I did leave the following comment:
I'm retired from a lifetime in the oil and vehicle profession, this is the most complete video I've seen, thank you. A minor nit re: octane ratings - you correctly denote engine knock sensors should not be in knock mode as a routine, then go on later to say using less than recommended octane is fine when "recommended" but not "required". This is not true - the WAY the knock sensors work is by detecting knock repeatedly in order to retard ignition timing - first in short time mode, then in long time mode. This is UNDESIRABLE. It will cause damage over time to cylinder parts. For those wanting maximum engine life (cars are so expensive now), this is important. Owners SHOULD use the recommended and required octane fuel, and only use less than recommended octane fuel on rare occasions where they can not find recommended octane fuel.
One final note - using higher than recommended octane does two things: (1) promotes incomplete combustion because the ignitability of the fuel is higher than the engine can easily combust, (2) leaves unburned hydrocarbon deposits for the same reason.
The conclusion is to always use fuel with the octane rating in your owner's manual with top tier additives to maximum engine life. Period.
Edit - this still does not answer HOW mid-grade octane gas behaves in engines recommending it, like our HEMI's, due to 89 being blended 87 / 91.
Maybe I'll write the "Shell Answer Man" (70's flashback). When I wrote them last year about something, they actually gave me a useful answer.