I have a question for everyone. What octane should I use in my new F350. I was always told to go with the highest octane avaible if you really like your vehicle. This is because the lower octanes are sometimes not good for your engine. But if you don't really care about your vehicle, just go for the cheap stuff. From my research with octane, I have used the 91 octane before in other vehicles, and received better gas millage because I was getting a better burn, and more power. I know the V10 minimum required fuel is 87 octane, that's what it says in my handbook. But wouldn't be better to put the 91 octane in the truck. Is 91 octane better for your truck, or should I be using 87 octane. I have read many different opinions on this and just wanted peoples feedback.

 

Use 87.

91 is not a better fuel for the V10.

What research are you referring to?

 

Monsta is correct on this. The higher octane fuel burns slower and thus can still be "burning" as the mix is travelling thru the exhaust valves then causing burnt valves over time.

 

87 is all I run even with a 10,000lb trailer.

 

The rule of thumb for ALL gas vehicles is to run the lowest octane gas you can that does not ping or knock when you run it.

 

I use 87 Octane without any pings. I towed a 26' TT with my V-10, on 87 Octane this past summer up hills and the famous "grape vine" while holding 55MPH and motor turning 4000 RPM, no pings, no nothing, my baby just kept on keeping. I too, have heard that higher Octane fuels burn slower and hotter, thus resulting in burning valves over time. It's my understanding that high Octane fuel is okay when the motor is old and tired, and has about 150k plus miles on it to give it a little more "Umph". Then that way, by the time the valves are toasted with excess carbon buildup (burnt), and discolored metal on the valves, the motor by then will have around 200k.... In some cases, +- 10 to 20k ready to be rebuilt.

 

The real problem with running higher octane fuel in a computer controlled engine is that it fools the computer into thinking something is wrong with the engine. The way the computer develops such amazing power and smoothness is by advancing the timing until it can just sense spark knock and then backing the timing down until it runs smoothly. It does this many times per second and when you put in higher octane fuel the computer often cannot advance the timing enough (remember it has limits within which it must function ) to get spark knock and it thinks something is wrong so it USUALLY pulls out a LOT of timing and the engine runs crappy!

 

Not to disagree with you. You are right on the newer modern engines that have computers. Infact all new engines have computers and it does mess with the engine timing. But going back 20 years when not all engines had computers and using high octane fuel did the same thing (burning valves). No one has ever complained about an engine running crappy on high octane (that I heard of). I ran three tank fulls of 92 octane when Union 76 used to sell it. My truck at the time had 6000 mi on it. I never noticed anything running wrong on the truck, in fact it was just a little bit snappy-er. Not even sure shure it ran better or was just my imagination. I did get better fuel milage though, about a 1/2 mile per gallon. So it was not enogh for me to justify the extra money to buy high octane. When I switched back to 87 octane, I don't think the engine ever noticed, it never pinged or nothing, even when I punched it. and held it there.

 

Same here, I've run 89 or 91 octane in my rig, and noticed no difference other than maybe mentally, and even that is suspect due to my mental condition (nyuck nyuck). When you chip your ECM the timing is changed enough that you must use the higher octane, or the engine will ping. But standard factory equipped V-10's run on 87 octane. You could buy a higher octane but why ? There's no benefit at all other than just costing yourself more money. But remember Big Dually, SOME people pay an extra $6,000 for a diesel, so it's not unlikely that someone would buy premium when they don't need to either. (OK, I'm braced and ready for the oil-burners to flame me, come on !!)

 

87 unless running a performance tune program.

 

You don't list a location but remember at altitude you can get away with even lower octane, can't remember why at the moment though.

In Denver I run 85 most of the time as it is the standard octane, 87 being mid-grade and 91 overkill. I get better gas mileage on the 85 and zero problems otherwise.

 

I have a programmer with the high octane tune and I still use 87 pulling my car hauler and have never noticed a ping. I really dont think that it advances the timing that much anyway. I havent noticed any difference with any of the fuels. When traveling I can't compare apples to apples because of road conditions and hills. I would like to know if there would be a gas mileage increase. I doubt the increase would justify the cost for the higher octane

 

Mine has run on 87 for 3+ years. It has made a light ping under load. Took the camper for 2300 miles and used 89 octane for the trip...not one ping. Now its back to 87 unloaded...still no ping.

 

Describe "ping". Sometimes pulling a hill from a stop, mine sounds like a Diesel until I get the RPMs up. Is that a ping, or is that a knock?

 

If they ping it should not be for long, since the knock sensors in the intake valley detects this and retards timing.I have the tuner, and run premium all the time,and on occassions when i have it nailed, on the 3-4 shift it will ping for an instant.I attribute this to bad gas.I was told by a Ford tech that some V10,s the cylinders have wavy cylinder bores and the sound from the piston in this bore is enough to cause the pcm to retard timing. Dont know if that is true or not. I have run octane booster a few times and it runs real well when i do.If anyone has a chip or tuner they better be running premium, just because you cant hear it pinging does not mean you are not harming the engine.

Hang 10, pinging should sound like bb,s in the combustion chamber, high pitched.