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matt.brown · 02-21-2012, 05:10 AM

I have received a lot of excellent advice since joining this forum. I just want to thank you in advance for sharing your wealth of knowledge and experience it has really been helpful.

Okay now I have another question. Which octane fuel is recommended for a Ford V10 6.8L engine. I've read where it doesn't pay to run anything higher than 87 octane. Any advice?

HD4Mark · 02-21-2012, 05:41 AM

Less than scientific for an answer but when we had the class C with a Ford V10 we never ran anything but 87 and never had a problem.

They used to say if your car doesn't "ping" with lower grade gas, don't waste your money on higher octane. That said our little toad doesn't ping on 87 but sure seems to run better on 93.

Wizard · 02-21-2012, 05:53 AM

It was designed to run on regular unleaded. Any time you change, the ECM has to re-learn how to run on what you give it.

Had a V-10 truck pulling a 5er and had a V-10 motorhome. I played around with mid grade gas several times but could not see any difference except the cost was higher. MPG even stayed the same, though I never stayed with the higher octane for more than a few tanks.

njs42 · 02-21-2012, 06:21 AM

This is my take:

Use whatever octane the owners manual or manufacturer says is best. Except for high preformance highly tuned or specifically designed engines 87 octane is just fine and there is no benefit in running higher octane. If you ping have your engine tuned before moving to a higher octane.

TXiceman · 02-21-2012, 06:24 AM

Go with the owners manual. We had a 1999 V-10 in a Minnie Winnie and it was not sensitive to fuel...all it wanted was lots of it, so it got what was cheap and never a ping or shudder.

Ken

Dunner · 02-21-2012, 06:48 AM

Given the exact same engine conditions, timing, compression, etc, if it doesn't ping on 87, you will not gain performance with higher octane. Lower octane burns faster than higher octane, so you should get more power with lower octane.

Hipshot · 02-21-2012, 07:24 AM

Be careful some places, like northern Texas, have 85 octane. If your in the habbit of pushing the cheapest button like I am you will get a surprise about 10 miles after fillup. I did that on a trip to South Dakota. My Silverado ran like a dog for a couple of hundred miles. Tnen I filled up with 93 and all was well. My Ford V10 runs great on 87 and I am very carefull to check which button I am pushing.

Iron Man · 02-21-2012, 07:47 AM

With engines with a "knock sensor", if pinging occurs then the timing curved is changed. You will not hear the pinging but the timing will be retarded to stop the pinging, hence the poor performance.

Rick Long · 02-21-2012, 07:52 AM

Buy GOOD gas with proper additives and 87 octane.

jlyon69 · 02-21-2012, 08:06 AM

The V10 is a low compression engine and is meant to run on 87. The higher the compression ratio, the more octane is needed to prevent detonation, aka spark knock (the fuel igniting before the spark plugs does it). Many folks think the higher the octane the hotter it is, not really so. Low octane will ignite under lower pressure than high octane and high octane burns slower. Just like all others have stated, no spark knock, you're good to go on 87 and 89 or more is a waste.

One time with my 10.5 to 1 compression ratio motorcycle I was forced to use 85 octane. I put in 4 gals and went across the street to a trucking business and bought 1/3 gal of diesel. It smoked a little but sure didn't spark knock or fry my engine!

rmmpe · 02-21-2012, 08:21 AM

Be aware that many fuel stations in the higher elevations out west will have 85 Octane, which Ford recommends not be used.

Consequently, you may have to use the 89 Octane fuel as we've done many times.

Dunner · 02-21-2012, 08:53 AM

A lot of people go by what the greedy oil companies brain washed into their daddies head and was passed on to them. "Super", "Premium", "High Test", etc would give them more power.

If you don't believe what is being preached here, in a safe place, run a line of 87 and a line of 92 on the ground. Light them at the same time and see which gets to the end first. Do you want slow burning gasoline in your engine if you don't need it?

dieselclacker · 02-21-2012, 08:56 AM

You can use 85 octane at the higher elevations where it is sold with no problems. You will suffer a power loss at lower elevations with the same fuel. There is no advantage to using 89 octane in an engine that is designed to use 87, unless you consider the higher cost per gallon an advantage.

W4MBG · 02-22-2012, 08:29 AM

i have a car that gets insane gas mileage. about 76mpg. every little thing makes a difference. lower octane yields better mileage. higher octane gets you more power. assuming the engine adjusts with a knock sensor (fairly modern engine). every step up in octane lost me about 3 mpg.