Gas for Ford V-10

What naturist said

I pay no attention to the octane of the regular gas we use in our V10 Class C motorhome. We have traveled only as high as 9600 feet in it and in going up to that altitude, or at that altitude, there was no pinging or noticeable loss in pulling power.

(BTW, very rarely will the ambient air be at a high temperature at those kind of altitudes ... so any interaction issues between performance versus gasoline octane versus high air temperatures at high altitudes should be minimum or non-existant with a modern ECM based engine if everything is working correctly.)

That Ford engine computer does it's thing just fine in our 2005 rig.

I will throw in a curveball. There are tunes available for the V-10 which can allow it to use higher octane fuels and make the most use of it. Supposedly, places like Five Star Tuning have tunes which will allow an engine to use 92 octane, but get 1-2 more MPG from that than the cheap stuff, making it more cost effective. However, that is anecdotal evidence.

I do have to ask: E85 or 85 octane? Totally different animals. 85 octane is one thing, but E85 (15% gasoline, 85% booze) can damage both a generator (Onan expressly forbids using it) and the V-10 (it isn't Flex-Fuel.)

When we were near/at Glacier National Park a couple of years ago, we used 85 octane in our V10 and it ran just fine. No knock/ping, and it didn't have an effect on the mileage. (Only mileage effect was the mountain driving.)

Edit: We only ran one or two tanks and it was used before we got down out of the higher altitudes.

When we were in Yellowstone 2 years ago I filled up with e85 and I do not know if it was just bad gas or if it was the e85 but our generator would not run. Once that fuel was used from driving went to the highest octane and it fired right up.

Yaj wrote:
I'm not a expert, but I did stay in our motorhome last night, so here goes.

Geez, if I had known that, I could have avoided 4 years of college working on my Engineering Degree.:S
Though I did a lot of studying on the effects of alcohol in the human engine:B, so I guess it wasn't a total waste of time:)

Case in point, if I had a rich enough ratio of alcohol in my "engine", I notice that my seals would leak too.....usually in bed:(

This is out of the Ford
v-10 manual:
Octane recommendations:
Your vehicle is designed to use
“Regular” unleaded gasoline with
pump (R+M)/2 octane rating of 87.
We do not recommend the use of
gasolines labeled as “Regular” that
are sold with octane ratings of 86 or lower in high altitude areas.
Do not be concerned if your engine sometimes knocks lightly. However, if
it knocks heavily under most driving conditions while you are using fuel
with the recommended octane rating, see your dealer or a qualified
service technician to prevent any engine damage.

am sure they have a reason to put it in plain English.

Some useless and ignorable posts here, but TucsonJim gave some great info.

I wasn't clear that there is a difference between 85 octane fuel and E85 (E15). E85 is the high alcohol stuff you should avoid.

Auto Alliance and Global Automakers

The CRC study released today showed adverse results from E15 use in certain popular, high-volume models of cars. Problems included damaged valves and valve seats, which can lead to loss of compression and power, diminished vehicle performance, misfires, engine damage, as well as poor fuel economy and increased emissions.

"Clearly, many vehicles on the road today are at risk of harm from E15. The unknowns concern us greatly, since only a fraction of vehicles have been tested to determine their tolerance to E15," said Mitch Bainwol, president and CEO of Auto Alliance. "Automakers did not build these vehicles to handle the more corrosive E15 fuel. That's why we urged EPA to wait for the results of further testing."

The potential costs to consumers are significant. The most likely repair would be cylinder head replacement, which costs from $2,000 (to) $4,000 for single cylinder head engines and twice as much for V-type engines.


If you fill up with 85 octane at altitude, burn it off before you drive a lot of hills below 5000 ft. I understand the V10 runs a comp. ratio of 9.2:1 and would probably not be happy being loaded and heat soaked, driving uphill on a nice (and hot) California summer day. I suppose you could pour in some octane boost or top off with high octane to balance out your tank as well, then just keep filling with your normal fuel.

Jose

I live in the Denver area and have been using regular grade 85 in my 2010 V10 with no problems. This motorhome has been over 10, 000 ft several times, with car in tow.

n7bsn wrote:
You may note that those that aren't real experienced at "real" mountain driving (ie over 5000 ft) think that 87 is "required".
Well, 85 at real elevation preforms like 87 at sea-level. That's why "regular" is 85 at elevation and 87 at sealevel

Here is the best advice, RTFM (read the ford manual) they know the engine and it's requirements better then any "internet" "x-pert"

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