Should I add an octane booster / additive? (Weird problem)

[Ralph LoGrasso]

I realize many of these don't work, but which ones actually do? I think I'm in need of one, but what do you think? Here is my situation.

About 3 weeks ago(during the huge spike in gas prices), I filled up my car ('01 SS) at a Sunoco station. 93 Octane. I do not drive the car very often, maybe once a week or so. The next time I drove the car, I put about 60 miles on it, and during that time my SES light came on. I scanned the comptuer and it threw two codes (two of the same) P0420 Catalyst Efficiency Below Threshold (Bank 1). I deleted the codes took a ride around the block, and all seemed fine. No SES. The next time I drove the car, the SES light came back on, and after I delted the codes, as soon as I restarted the car, it threw codes again. SES light would not go off. During this time I was getting extremely bad gas mileage ~ 10mpg or so. Leading me to think it's an 02 problem.

Fast forward to last friday. It's once again time for gas, and so I put in about 6 gallons of 93 octane Exxon, there was about 6 gallons of the Sunoco left in the tank, as well. I drove the car today for the first time since Friday, and although I didn't put too many miles on it, I seemed to be getting my normal gas mileage. Thinking my problem might be solved, I deleted the codes again, and drove the car around the block-- no SES light or codes. Everything seems to be fine, but only time will tell, haha.

So, to not turn this into a complete novel, I'm thinking that I either got some real bad gas from the Sunoco station, or possibly 87 instead of 93(I've heard of this happening to people), and it caused a problem with the ECM/02 Sensors. And now that there is good 93 in there, it's remedying the problem, and hence better gas mileage and no codes.

The car didn't ping or knock or anything (as it probably should've with 87) with the Sunoco gas, but it did feel like it bogged a couple of times when I got on it hard, it may have just been the way I launched the car, though. What do you guys think? Should I throw some octane booster in the tank for good measure?

Thanks for any help,

edit: cliff notes -- car threw codes for either cats or 02 sensors (generic code), codes would reappear as soon as i started the car, after putting in fresh gas, and deleting codes, they didn't come back. Thinking problem was caused by bad gas.

[myclone]

IMO you got hold of some crappy/stale gas. Everybody and their brother is buying 87 only so you know the 93 has been sitting there in the stations tank for weeks.

FWIW you can mix some xylene thats available at any paint store in a 3 to 1 ratio and make your own high octane to see if the charactoristics of the car change for the better. If the drivability comes back by doing this then youll know that it was just bad gas.

FWIW II/FYI
I did some data logging using my syclone which is extremely detonation prone (crappy combustion chamber design) to compare gas brands. Suprisingly exxon was the worst gas as far as knock retard where as Shell produced the least amount of knock while BP and AMACO(sp?) were even right behind Shell. As a matter of fact Shell/BP/AMACO only produced 1-3deg of retard where as exxon was 6-7 degrees of retard due to detonation. No more exxon 93 for me since.

Oh btw, I did the same data logging using some off the shelf octane booster ("104 Octane Boost) and it did absolutely nothing except turn the plug porcelin red when I got really agressive with the mix trying to see an improvement in KR. Off the shelf octane booster=snake oil from the data Ive seen.

[yody]

supposedly octane booster only increases you octane by tenths of a point not full points so you would get like .1 more octane, not 94 octane but 93.1 plus I'm not sure if htey are good for your cat are not. Definetly snake oil

[tyler mckee]

you can use toluene to boost your octane too