In my '99 Cad Deville, I started using mid-grade ( 89 octane ) gas which performed o.k. with no knocking/pinging. I used that for several tank-fulls. Because of high gas prices, I thought I would go even lower in octane, so I tried 87 octane. I have put several tank-fulls of that in and still have not noticed any problems at all.

Has anyone had bad experiences in doing this? example: engine light, bad O2 sensor, engine "dieseling", etc etc ?

 

Hey Silver: Gasoline as a rule gets a different formulation from summer to winter so it would depend on what season that you mean for the ping/ knock problem. I personally use only premium in my caddy because it's a big block. A big engine needs big gas.The price is secondary because I enjoy the extra power I get from high test. Summer gas on the other hand can be absolute crap and your engine will show it.They add more H2O in summer and not so many other additives. Hope you are enjoying your ride all the same , take care.

 

Well that's all in good for you...not what I had asked though

What I want to hear is from people that have done what I have and had ANY bad experiences from doing so.
or have had friends that did the same.

 

Yes some ping especially during the hottest days of the year.
The computer will reduce ignition timing when it detects lower octane but only so much and its not instant.
If you don't mind the reduced power then run the lowest grade you can with no ping.

Otherwise it will not damage o2 sensors or cause dieseling.