New Chevy 6.0L gasser -- Octane?

I started running 91 octane gas in my motorhome because it performs better, and also better mileage. Test it for yourself.

Fred.

All modern engines with computers have "knock sensors" in them.. Even my 97 F150 5.4 had one and the computer uses the knock sensor to determine how much timing it can run.

The theory is that if you run higher octane, the computer will advance the timing and therefore net you some more performance which can net you some mpg if you can still keep your foot out of it..

I tried it on my 97 for about 3 tanks of gas running empty and didn't really notice any change.. I didn't do it towing because it ran fine on regular and @ 10 mpg, I didn't want to pay the 20/30 cents more per gallon.. :)

I'm curious if it'll make a difference on my new Ecoboost, but so far I've only run regular and I've still not gone WOT with it, nor needed to yet... ;)

Good luck!

Mitch

I have 4,000 something on my 13 Ford 6.2, and the last 500 miles were towing with fresh 91 premium no alcohol. I was towing in fairly steep hills alot of those miles. It seemed to me that I had less down shifting, and an over all happier sounding engine.

Imagination? Maybe, but I don't think so,

Jerry

I agree to just try it for three tanks and you will know based off real world testing.

Knock sensors never advance the timing. Timing is set at a base table and if knock is sensed they will retard the timing until knock is no longer sensed and then return to the base table.

With modern computer control, engines are monitored so tightly that even slight changes in weather or altitude can make a difference in what octane to use for most efficiency. For instance, on a hot day at high altitude you will be able to get by with regular gas or on a cool or cold day you might have to use premium to keep detonation away. Same way with altitude. The closer you are the sea level the more octane you might have to run for best efficiency.

As you can see, it can depended on a lot of things. Bottom line is, the OP is just going to have to try different octane fuels and see for himself what works best for his situation and engine.

This makes me wonder about a lot of comments I've read in other places. I read that others buy gassers instead of diesels because the fuel is cheaper even though the diesels get better mileage. Today's fuel prices where I buy: Premium - $3.50, Diesel - $3.54.

My '11 GMC 6.0 calls for 87 so I burn 87. If it needed higher octane it would be labeled as such. I have used 91 and did not notice any difference.

My Acura is labeled for 91 and says 87 is optional. There is a big difference in performance and fuel mileage with the 91 both for the good. I think that buying a higher octane rating than what the vehicle was tuned for will do more to lighten your wallet than anything else.

I run 87 in mine, works fine for me.

As far as the diesel to gas spread. It has tightened up around here to about 40 cents cheaper for gas it is almost always 60-70 cents more for diesel but I have seen as high as a 90 cent spread.

I don't know where in VA that other guy is but I can get unleaded 87 around here for 3.20

I think they run fine on 87 octane. If I remember correctly, that is what GMC recommends. That being said, if you can by 91 octane that is ethanol free, you will probably get better mileage simply because it doesn't have to make popcorn too...

DavisK wrote:
This makes me wonder about a lot of comments I've read in other places. I read that others buy gassers instead of diesels because the fuel is cheaper even though the diesels get better mileage. Today's fuel prices where I buy: Premium - $3.50, Diesel - $3.54.

You are fortunate. Right now around here diesel is 40cents more then gas and has been higher. Makes one think more about the diesel/gas decision as far as fuel costs are concerned.