As you can see from my signature, my DD is a 6.0 PSD. But I also drive a 2002 class C motorhome with the V10. It has the Banks Powerpack, drives great. I searched a bit on here, but could not find any answers to my question.

I made a mistake yesterday, long day of driving, first time in northern Utah. Pumps offered left to right: diesel, 85, 87, 89, 91. I screwed up and chose 85, me being cheap I guess. I put about 27 gallons into a 55 gallon tank to fillup. No noticeable issues, filled up next stop with 35 gallons of 87. I was driving some steep passes in Montana later, without any issues. The more I thought about it though, I just wondered if I should not add some octane booster just to cover my butt. We are parked now for a few days in a remote spot, but will hit a gas station soon.

Any thoughts, should I be concerned? Should I fillup with 89 to kind of balance my screwup?

Any feedback is greatly appreciated, have a good day.

 

If you had no pinging there is nothing to worry about. I usually use 89 octane if pulling a heavy load thru the mountains. You can use 89 for the balance of the tank then go back to your usual.

 

DO NOT..... use octane booster in your motor. I have seen one to many ppl use it and it has caused burn marks on their pistons. As stated if you didn't hear pinging you should be okay. Just make sure on your next gas fill up to run a little higher octane to try and even it all up.

 

The 85 octane is very common in the higher altitudes above 4K feet, I use it all the time without any problems. The only time you may get some ping is when you go back down to lower elevations but that's easy to cure by blending in a little 89 octane or just run it out and go back to 87. I try and judge my fill ups when leaving the higher elevations so there isn't to much 85 left in my tank.

Denny

 

Thanks for the replies. I will use a partial fillup of 89 next stop, and that should do it. Live and learn, your help with this is appreciated, this forum and the 6.0 are a real blessing.

 

The V10 has a knock sensor, and if the 85 octane caused ANYTHING, the knock sensor will pull up to 4 degrees of timing to keep it from pinging.

Not a big issue, especially when you put 87 in it so soon after. If anyone else is ever stuck with this again, just put an equal amount of 89 octane (or a smaller amount of 93) in it to counteract it.

The way they figure octane is basically an average of all the molecules in the gasoline. Now, I know, that's not technically accurate, but close enough for the layman. If you mix an equal amount of 85 octane and 89 octane you wind up with 87 octane.

 

Just as long as you stay in the higher altitudes the 85 is just fine and everything will run normally because it's blended for the thinner air so your truck will not even know the difference, the only time you will have to blend is when you come back down and only if you have a lot left in the tank.

Denny

 

I live at 7,000 ft. elevation and have used 85 octane on my 2001 V-10 since new.

My understanding is that you can use lower octane at high altitudes and it is equal to 87 or 89 octane at lower altitudes.

 

Art,I've found one exception to this date. '05 Excursions with the 2V V10 do not have a knock sensor. Weird,but true. 85 Octane isn't an issue at high altitude,and is very common in mountain areas.
JL

 

JL, thanks for filling me in on that, that's WEIRD.

 

It really is. Being the last year of the model, I think they started "thrifting" items to save money on the model to make it more profitable, maybe hoping to keep it around for an engine/trans changeover like the Superduty pickup got in '05.
JL

 

While we're on the off-topic subject, isn't the knock-sensor somewhat emissions-related ?