Fuel for Gassers

Waste of money!
Run 87 octane.

you will receive opposing answers on this as I recall from other threads on this and other RV forums. It is a frequent question.

enblethen wrote:
Waste of money!
Run 87 octane.

waste of $. run whatever octane grade your owner’s manual calls for.

I’ve proven, on both of my own, and several other m/h’s that the lack of alcohol and related contaminants results in enough extra mileage to more than offset the increased costs. On my older rig my mileage increases about 23% by running ethanol-free fuel.

So here’s how that plays out in my case, round-trip to south Florida is about 3,000 miles. My rig gets 7.32 mpg on regular gasoline with ethanol in it. So that trip is 410 gallons. If it has 10% ethanol then it’s 41 gallons of ethanol and 369 gallons of gasoline.

On ethanol-free premium my rig gets 9.0 mpg. That same trip then uses 334 gallons of only gasoline. If your $0.60 / gallon is close then that trip costs an ‘extra’ $200. Except I bought 76 less gallons of gas. If we use a $3 / gallon average price that is $228.

So if I ‘waste’ $200 on premium but spend $228 LESS in fuel, it looks to me like I’m up $28....... and that’s before we get into the 35 gallons less gasoline and 41 gallons of ethanol I DIDN’T burn on top of the 334 gallons of ethanol free gas.

I'd run it if you feel you need a little more power. :)

Any modern fuel injected gas powered engine these days are all computer controlled and have knock sensors in them. Lower octane fuel will produce knock in an engine sooner when it's being worked hard and thus the computer will start to "******" the timing so it don't knock no more.. This takes away a bunch of power in general. Just like distributer timing did back in the day of carbs and points.

Running 92 octane keeps the knock sensor at bay for a little longer and keeps the timing up for more performance when you are working the thing in my experience.

Sure, putting around town and no load, 92 ain't not gonna do a darn thing for ya..

Assuming a V10 Ford here too? Even my old 97 F150 with a 5.4 had those knock sensors and would run better with 92 in the tank (you have to let a tank or 2 go thru it so the computer calibrates for it over time to really see any change.)

Just don't think if you put half a tank of 92 in and then expect the world to change is just not going to happen.. :)

Anyway, I learned this especially on my little 13 F150 with the dreaded "ecoboost" in it..

I ran 87 from day one and towing a little #5000 TT and it did fine.

Fast forward several years and I upgrade to a new #7000 TT... I go over the same passes I'd gone over for years. Well, it could hardly get up the same grades without being in a lower gear (3rd) and running slower (50) then before... And running hotter to boot.

Next trip, I ran 92 for a couple of tanks before and then towed the same pass, I was again back to 4th, running any speed I wanted (55-60) easily.. And keeping the temps in check and not getting 7 mpg.. I am now back to it's usual 9-10 mpg towing as I had with the old trailer..

Says so in my owners manual too.. "Run Premium when towing, but it'll run fine on Regular otherwise.."

Yes, it's more expensive and I only have a 35 gallon tank, so having some 75+ gallons on your class A, might make a difference...

I've hit the $100 limit at several stations that have that limit set a number of times.. My last few camping trips has been over $100 fill ups and that's for only around 25 gallons of gas for the 92 stuff....

But, I would rather pay now, then pay later for beating the engine up.. I'm over 103,000 miles on my old Eco and it still pulls as strong as it did when it was new..

In the end, do whatever works best for YOU... Not what a bunch of internet hacks says... :)

I'm just saying what has worked for me.. To anyone else, I'm probably talking out of my a$$ and have no clue.. Maybe, but it's working for me. ha, ha... :)

Good luck! Mitch

I ran 87 octane through the Rockies on multiple occasions with my 3.5 EB and light (3500 pounds) and did great. I tried corn free fuel and gained almost nothing in MPG. It was not worth the extra cost to me. If I towed a heavier TT maybe it would be worth the money.
My EB has 215,000 miles and I plan on using it through the Rockies on more trips. It runs great. My only major repair was an exhaust manifold at 205,000 miles.
I still get 21 mpg while not towing on the highway and 12 mpg with the TT on the ball.

Alex,

The 7.3 V-8 is not the Ford V-10. So, what many will tell you is possibly wrong. Very early in your experience with this coach, you should buy a "Scan Gauge" and plug it in. It can feed you instantaneous fuel rate and average as well. Try different fuels. Write the odo on the receipt. Figure out which works best for your driving style.

The alcohol in "motor fuel" adds nothing but cost. The problem is that is now more common. At one time I monitored how much the alcohol contributed. The loss of fuel economy (in crease in fuel rate was a mirror of the alcohol content.

Matt

waste of money UNLESS you drive not frequently and have access to premium fuel with no ethanol.

I believe the 7.3 V8 calls for 87 Octane.

Alex and Tee wrote:
I believe the 7.3 V8 calls for 87 Octane.

It runs fine on 87 when empty. I started using premium when towing and with 22.5K, it is better to have more power.