Higher Octane Gasoline

[mre]

Does anyone use a higher octane fuel in the Ford Class A or Class C motorhome?

The User Manual says this:

Your vehicle is designed to operate on
regular unleaded gasoline with a minimum
pump (R+M)/2 octane rating of 87 or
regular unleaded gasoline blended with a
maximum of 85% ethanol (E85).
Some fuel stations, particularly those in
high altitude areas, offer fuels posted as
regular unleaded gasoline with an octane
rating below 87. The use of these fuels
could result in engine damage that will not
be covered by the vehicle warranty.
For best overall vehicle and engine
performance, premium fuel with an octane
rating of 91 or higher is recommended. The
performance gained by using premium fuel
is most noticeable in hot weather as well
as other conditions, for example when
towing a trailer.

I have a 2022 Ford Ranger and the User Manual says the same thing. There was much discussion on this on the Ranger Forum. I started to use a higher-octane fuel and it made a difference in performance and mileage.

[DarkSideJeep]

Originally Posted by mre

Does anyone use a higher octane fuel in the Ford Class A or Class C motorhome?

The User Manual says this:

Your vehicle is designed to operate on
regular unleaded gasoline with a minimum
pump (R+M)/2 octane rating of 87 or
regular unleaded gasoline blended with a
maximum of 85% ethanol (E85).
Some fuel stations, particularly those in
high altitude areas, offer fuels posted as
regular unleaded gasoline with an octane
rating below 87. The use of these fuels
could result in engine damage that will not
be covered by the vehicle warranty.
For best overall vehicle and engine
performance, premium fuel with an octane
rating of 91 or higher is recommended. The
performance gained by using premium fuel
is most noticeable in hot weather as well
as other conditions, for example when
towing a trailer.

I have a 2022 Ford Ranger and the User Manual says the same thing. There was much discussion on this on the Ranger Forum. I started to use a higher-octane fuel and it made a difference in performance and mileage.

When I still owned the 2018 Thor ACE on the F53 Chassis there was similar language in the owners for the V10. I mostly burned higher octane 91. Maybe once every third tank I would use 87 if the station did not carry 91 octane or when the 91 octane was particularly expensive, but I never put 85 octane. But My owner's manual explicitly prohibited E85 15% gas and 85% Ethanol.

[Mark_K5LXP]

Part of it is altitude. Low end gas here is 86 octane and my normally aspirated cars and RV run fine on it. Back when I did more cross country driving on the level and closer to sea level I would alternate tanks between low end and premium, and noted a consistent 10% or so increase in mileage with the premium. But the premium cost more than 10% over the low grade, so I usually will run whatever the vehicle seems to be happiest with. I used to have a "high compression" ford V6 and it would ping like mad with low grade, so ran mid grade in that one. But in terms of mileage alone I couldn't connect get there from here with the nominal premium grade mileage gain.

Mark B.
Albuquerque, NM

[MooseCountry]

Our Ram 6.4L recommends 89 Octane. Since it isn't sold within our entire state that's not an option, but 87 Octane gas can be used. However, 87 Octane isn't sold locally here. It's 40 miles to the next station on the highway that sells it. One pump at our high altitude gas station and it's 85 octane, only. That's what it gets.

[Ray,IN]

Octane does not produce more power. It reduces pre-detonation in high compression engines-spark knock. Engines have sensors to reduce spark knock by retarding timing, which will affect power and fuel economy.
Thus, buying higher octane than the engine mfgrs, state is required is a waste of money.

[azpete]

higher octane can cause burned valves, and pre ignition.
why not use what it was designed for.
run a fuel conditioner, like sea foam, or cleaner every 8 or 10 fill ups if you are worried.

[Spdracr39]

I had a dodge pickup and it said 87 octane recommended. Anything higher and it ran terrible. My toad says 91 recommended but actually runs fine and gets better mileage on 87. I think recommended is just that but if it says required you might want to pay more attention.

[DarkSideJeep]

Originally Posted by azpete

higher octane can cause burned valves, and pre ignition.
why not use what it was designed for.
run a fuel conditioner, like sea foam, or cleaner every 8 or 10 fill ups if you are worried.

I think you have that all mixed up. Premium fuel does NOT burn hotter than regular fuel. Premium fuel is more resistant to detonation or pre-ignition. Higher octane is the cure for pre-ignition. Pre-Ignition causes higher operating temperatures, knocking and burned valves.

Modern fuel injected vehicles can run on lower octane because the ECM adjusts ignition timing to prevent knocking. This adjustment comes at the expense of fuel economy and performance. Most drivers will never notice the difference of burning a lower octane when driven under "normal" driving conditions. Under heavy duty driving like a pickup truck towing a travel trailer or a motorhome with a TOAD traveling 70mph burning premium might be the difference keeping a normal operating temperature and overheating.
.

[Ray,IN]

Originally Posted by azpete

higher octane can cause burned valves, and pre ignition.
why not use what it was designed for.
run a fuel conditioner, like sea foam, or cleaner every 8 or 10 fill ups if you are worried.

Paul I think you typed that backwards; higher octane reduces pre-ignition/pre-detonation/spark knock in high-compression engines >13/1 ratio. That was the only purpose when lead was added to gas.

[Persistent]

Originally Posted by DarkSideJeep

I think you have that all mixed up. Premium fuel does NOT burn hotter than regular fuel. Premium fuel is more resistant to detonation or pre-ignition. Higher octane is the cure for pre-ignition. Pre-Ignition causes higher operating temperatures, knocking and burned valves.

Modern fuel injected vehicles can run on lower octane because the ECM adjusts ignition timing to prevent knocking. This adjustment comes at the expense of fuel economy and performance. Most drivers will never notice the difference of burning a lower octane when driven under "normal" driving conditions. Under heavy duty driving like a pickup truck towing a travel trailer or a motorhome with a TOAD traveling 70mph burning premium might be the difference keeping a normal operating temperature and overheating.
.

This ^^^ is the most authoritative of the posts here. This is the best advice. Follow manufactures recommendation for best results.

Engine design and testing is a major field of engineering. You would not want to take the time to understand how it all plays out. Trust the information that the design and manufacturing engineers provide.

[OldBaldFat]

Important to remember.

Everything we learned about engines and octane back in the 60's, 70's and 80's when we were learning to drive and learning to maintain our first vehicles, we bought. All the information went out the window, about three times over.

Now personally, I'll be happy to never set the points in a distributor again.

[Ray,IN]

Originally Posted by OldBaldFat

Important to remember.

Everything we learned about engines and octane back in the 60's, 70's and 80's when we were learning to drive and learning to maintain our first vehicles, we bought. All the information went out the window, about three times over.

Now personally, I'll be happy to never set the points in a distributor again.

MyMassey Ferguson farm tractor had points and condenser; now it has an aftermarket electronic module. (ever try to get a 3-cylinder engine to stop with a piston TDC??