The big gasoline question

[tkswan]

02 LS V8

Any danger of running +89 octane instead of the +91 octane gas that the car calls for? Some cities actually have a specific +91 grade on the pumps but in Texas it steps from from +89 to +93. Today I paid $3.92 for supreme (+93) at Chevron . Midgrade at +89 was $3.60.

I usually only buy from the oil rapists: Exon, Chevron, or Shell. I filled up once at Wallmart and the price was cheaper but the mpg went down and I needed to fill up again sooner than before. A full tank from the oil rapists goes father that a full tank of cut-rate gas. They could at least give me a kisss, a reacharound, something!

...and I complained about paying about $1.45 for supreme when I bought the car.

[shorod]

Technically if the engine's knock sensors are working along with everything else, you PROBABLY would not have a problem running the lower octane. But, keep in mind that the electronics of your engine are only designed to advance and retard the timing a finite amount. If going with a lower octane would require more adjustment than the car can compensate for, now you're risking damage to the engine. Is the risk to the engine worth the $0.32 per gallon savings? Ever priced a new or rebuilt engine for one of these cars?

The engineers that designed the engine and powertrain control system are not getting subsidized by the oil industry, so they have no good reason to suggest only 91+ octane fuel if there isn't a good benefit to using it. I don't think that meeting the horsepower rating is a good enough reason.

-Rod

[tkswan]

Good thing I didnt fill it with up with +89. I'll have an armored car meet me at gas pumps and the other half tank of +93. Since its actually 2 points over the recommended octane rating it should be ok untill it needs another fill up.

Thanks for the clarifacation Rod.

[shorod]

And if the car pings or has issues, you'll probably feel it (sluggish, hopefully you won't hear the pinging).

-Rod

[gcwimmer]

93 octane is predominate east of the Rockies and 91 octane is predominately west of the rockies.

[tkswan]

Thats strange. Im from Omaha and found +91 everywhere north of Oklahoma city. I live in Dallas and find +93 everywhere.

[gcwimmer]

I was repeating an article in Car & Driver about 2 months ago; they did not give a reason. Predominantly does not mean exclusively, California and Nevada it is difficult to find 93 with the suppling refinery's being in CA. I believe it has something to do with the additive they use to bring up the octane being highly carcinogenic and CA stringent pollution laws.

Dallas, TX is east of the Rockies.

[Quik_LS]

and remember - is the car has to retard the spark to keep it form knocking - you will get both worse mileage and performance.

[tkswan]

Originally Posted by gcwimmer

I was repeating an article in Car & Driver about 2 months ago; they did not give a reason. Predominantly does not mean exclusively, California and Nevada it is difficult to find 93 with the suppling refinery's being in CA. I believe it has something to do with the additive they use to bring up the octane being highly carcinogenic and CA stringent pollution laws.

Dallas, TX is east of the Rockies.

YesIi am aware of where I live and where the Rockies are. The point was that +91 is found east of the rockies in many places.

[danielsatur]

If the car runs bad, use some Octane booster,or injector cleaner.


MCGIVER

[bandaidmd]

mine will spark knock (or whatever other fancy term you care to use) on 87 . its only another 3 bucks to fill up with the correct grade of fuel so why risk it.

[2005LSdude]

Back when I first got my car I also tryed the 87, then 89 and had to use 91 , mine didnt really knock but pinged on 87, but careful with 89, could not hear it ping on 89 until I did a check with a bridge with concrete sides, a on ramp to a hiway is a good place to check if it has concrete sides , then I could hear a light ping while accelerating up on ramp, so I thought damn gonna have to use 91, don't want to ruin engine.