In an interview recently, a NASCAR driver indicated that there are no differences between brands of gas. Most importantly he said that no cars require premium grade
(93 octane) gas.
Obviously with fuel at an all time high and premium selling at a 20+ cent premium this becomes an issue.
I know what the manual suggests. However, I was wondering if anybody has used regular for any period of time and if there were any ramifications?
Anybody?

 

$.20 more per gallon times 13 gallons - $2.60

I don't consider $2.60 an issue.

 

In most cars, using 93 octane instead of say 87 octane is a waste. Octane is really just a measure of resistance to detonation. The old rule was, if your typical car doesn't ping or knock on 87, just use that. Computer engine management has changed this a bit with some cars having the ability to retard timing to compensate for detonation. So in these cases, the old rule no longer holds true, you might be able to run seemingly fine on 87 in a car that requires higher octane. The downside there is, you have less power than you should do to the ECU compensating for lesser gas.

Higher compression leads to detonation, our cars have a very high compression from the start at 11:1. Carbon deposits in the cylinder heads of older engines also raise compression, this is a reason older cars develop a knock or pinging sound when doing things like climbing hills. So given that fact, it seems entirely reasonable that our cars do in fact require high octane gas. I'd never put anything less in mine. Even if your car does run seemingly fine on 87, the engine is tuned for higher octane, it's possible you won't be getting the power your engine should be producing.

 

Thats your first mistake.

 

Oil, gas and religion - 3 topics subject to great controversy on the internet.

The only differences between brands of gasoline have to do with their additive packages. Even so, often the same gasoline can be found at stations that market different brands. However, you are more likely to receive fuel with better additive packages from stations that carry branded fuels (like Exxon, Amaco, BP, Chevron, Shell, Mobil, etc.).

To address your question, octane ratings are set by federal standards and can give improved performance for two reasons.

1) On old cars without OBD controls, higher octane fuels can be used to eliminate predetonation (pinging) issues once carbon deposits build up in the combustion chamber (raising compression). Since these cars do not have knock sensors, you can do substantial damage to the engine if operated while predetonating.

2) New cars, like the S2000, have OBD II control systems. This allows the ECU to control engine timing if it detects predetonation. This will mean that the engine will run safely, but you will lose power. So, yes, you can operate modern cars on lower octane fuel (87-89 RON) that recommend higher octane fuel (91-93 RON) without causing damage. However, you will not make as much power (due to the timing being retarded by the ECU) and you will likely experience reduced mileage.

I choose to operate my S2000 on 91-93 RON fuel. It allows the engine to perform as intended, and gives me slightly better gasoline mileage compared with running lower octane fuel. In a car with such high compression and such a high redline, this is the safest (and most fun) course of action.

 

....detonation is BAD. ECU will compensate by cutting power.

john

 

I didn't see the interview, but my friend was telling me about it, I believe it was on the Today Show. From what I heard, the NASCAR driver actually said that higher compression engines can benefit from higher octane. But he also said that the brand of gas is not important. Interestingly, either the most recent or second most recent issue of Car and Driver just had an article about "Top Tier" gas and explained that the additives in higher quality gas can be very beneficial.

 

If you can afford to properly maintain an S (i.e. tires, oil, etc), you can afford to put in decent quality gas. Don't skimp on a nice car. This isn't a civic.

 

I think anybody that has had experience with bad gas can safely say that there is a difference between brands. When I had a Jeep Wrangler, I would always just use the RaceTrack brand gas which was the cheepest in town. During cold mornings, the car would start then turn off again and I would always have to crank it twice. I changed gas stations to Shell and it never happened again. I haven't used cheap gas for anything other than my lawnmower since. I've heard too many stories about clogged fuel lines and minor engine problems with cheap stuff. Only name brand gas for me.

 

I have to use 93 octane in my Civic.