regular gas + octane booster= ? RON

MacLean

I have heard some dealership do not put premium in the cars that do require it. I know when I bought my G35 several yrs ago the sales guy said you do not need to put premium even though it says it. You will be fine with regular..... I was like WTF.

I took my mom's '11 Acura MDX to the Acura dealership yesterday for service. I started to talk to the guy that sold my parents the MDX & what fuel to use. He was like yeah it does say premium, but regular will work w/o any problems. He said he had a TL that he put 60k miles on it with regular & now has an MDX that has 20k miles with only putting regular gas. He has not have any issues or knocking noise from using regular instead of premium fuel.

I know my mom has had 2 TL's & is own her 3 MDX & only uses regular gas. She has never complained about any knocking noise from the use of regular gas. All Acura's require premium fuel as do BMW, Infiniti, Nissan, Lexus & etc. Oh my gf brother in-law has an Infiniti QX 56 that has 100-125k miles & he only uses regular gas. He has not had any problems of any sort from using regular gas.

I am not a mechanic and I have not done a study, or survey to find out how long would it take before a car that uses premium that is actually getting regular gas will last. I believe it really depends on how you drive the vehicle. If your vehicle has a supercharger or turbo charger, then you better put premium (maybe octane boosters if needed). If you are looking to take your vehicle to the track on the weekends, then you should put premium gas in your vehicle. If you are one of these people that like to go balls to the wall on the freeway, then you should use premium gas. If you are the type of person that only goes b/w 70-80 on freeways, then you could possibly get by with using regular gas (not sure how long).

In the end it is safer to just go with what is recommend (premium) for our vehicles, but it is also up to you as an individual.

Jordo!

You don't have to be a mechanic -- just read up on octane. Octane numbers indicate how likely it is to autoignite -- higher numbers are harder to ignite than lower numbers. Heat (from the air fuel mixture itself, or from lingering flame kernels from spark events) and cylinder pressure (either from piston characteristics or boost) can both cause fuel to auto ignite -- we only want the fuel to ignite when a timed spark event (i.e., when a spark plug fires) happens, not before and not after.

More ignition advance means less time for heat to dissipate from the piston head; higher CR's and or boost mean greater cylinder pressures. Therefore, octane requirements will depend on the CR of pistons, boost (if any) and ignition timing (other factors, such as atmospheric elevation, overall engine temps, etc. matter quite a bit too, but these are the key issues to keep in mind).

If the fuel ignites before or after the timed spark event, the pistons move out of time, creating stress on the engine internals, particularly the piston and rods. That phenomenon causes the "knock" sound you hear and it can result in cracked pistons or ruined rod bearings. Really bad autoignition events can create intense flame kernels that literally melt the piston head -- it will look like someone took an arc welder to it.

Anyway, the moral of the story is, you should use an octane no lower than recommended for the motor based on how it has been built and tuned. The requirements were determined empirically on an engine dyno when the motor was built and tested, and if you add forced induction, you pretty much have to once again determine octane requirements by observing power output and evidence of knock to determine new octane requirements to run safely.

Just saying "Ah, it'll be fine" is really taking an unnecessary risk.

It's worth reading up on so you know what you are doing and why it matters, and if you like cars, it's interesting stuff

__________________
Enjoy it. Destroy it.

Davey

Holy necro-bump, Jamesb1.

Welcome to the forums?

kenchan

Wowzers.. wat was the q again?..lol