Originally Posted By: OVERKILL
I can't see it having any real effect on valve deposits. I've read on here that it leads to less fuel dilution in the oil, which I would expect the theory behind to be less enrichment for anti-knock required with higher octane fuel.
I've mentioned this (less fuel dilution) after reading about it on another forum and after observing my own engine. Though I have heard people say about premium gasoline possibly reducing valve deposits, I agree I don't see how or why it could. I haven't seen any proof, just people saying what they thought. On a forum for my Impala, many believe running synthetic oil and changing it at 5K (or less) will help with the deposits and in the case of the 3.6 engine protect against timing chain problems. Not sure I agree with either but I have no proof either way!
In my area, premium fuel is usually 20 - 30 cents a gallon more, so it's not a big deal to fill up with premium (17 gallon tank). One guy on the Impala forum who uses the tuning software states there are different tables for premium fuel and I have seen a difference monitoring the fuel trims and the knock retard via Torque Pro.