What octane of fuel do you run with the 7.3l?

punkinhead said:
premium, i put it in everything,lawn mower, weedeater,4 wheeler and motorcycles. just do and always have. waste or not. makes me feel warm and fuzzy all over.?
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From what I have read, with autos, premium or regular, pick an octane and stick with it. Something about modern motors , computers and adjustable timing not liking to jump around so much.
I run whatever the vehicle calls for. Wifes turbo sees only premium, garden tractor and lawn equipment get premium also, no reason for it.
My car gets regular.
 
I've run 93 octane since day one, with 2400 miles on it now. Maybe I don't need 93 octane but since my tractor and 4 wheelers do, it's habit. Plus I ran 93 Octane in my 2018 Raptor while I owned it.
 
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Has anyone tried the 87 octane but ethanol free? Here 87 with ethanol is 1.66$ per gallon vs ethanol free 87 at 2.12$ per gallon. Supposedly better mileage with ethanol free, less corrosion issues.
 
JC_Tremor said:
Has anyone tried the 87 octane but ethanol free? Here 87 with ethanol is 1.66$ per gallon vs ethanol free 87 at 2.12$ per gallon. Supposedly better mileage with ethanol free, less corrosion issues.
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Ethanol was an issue for outboard boat engines, and still can be. As long as ethanol fuel isn't sitting in your tank for 2 months or more, its fine. If its sitting that long you should use a fuel storage additive. For small engines the ethanol can really gum things up (lawnmowers, etc). I use non-ethanol for the boat, lawnmower, etc.

For the Tremor I follow the owner's manual: 87 for regular driving, 91 or 92 for towing, and if I want to splurge and get every available drop of power I splurge for non-ethanol.
 
JC_Tremor said:
Has anyone tried the 87 octane but ethanol free? Here 87 with ethanol is 1.66$ per gallon vs ethanol free 87 at 2.12$ per gallon. Supposedly better mileage with ethanol free, less corrosion issues.
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I have 90 octane ethanol free here, and have run it on my last 2 tanks. MPG jumped and I can get 14.5-15 pretty easy on the hwy if not better.
 
I run 87 in everything I own, no matter if it calls for it or not... never had a problem with pre-ignition on a modern engine. They will adjust timing to prevent damage. There could be some minor performance increase on some engines, but I doubt a stock NA 7.3 engine is one of those unless there is an aftermarket tune that could take significant advantage of it.
 
Just picked up my 7.3 last weekend and am getting ready for the first fill-up, has anyone experienced any issues running 85 at altitude? I typically try to get gas at costco but they only offer 85 & 91 and I know Ford stressed 87 min. I can't imagine there would be any issues, especially driving unladeden/low load?
 
Octane is an index number assigned to the resistance of fuel to "pre-ignite" meaning it lights before the ignition system starts it.

Pre-ignition or detonation occurs when the flame front collides with itself and is typically caused by hot spots (IE carbon deposits) within the cylinder or combustion chamber that starts the combustion process by more than the intended ignition source.

Everything built within the last 3 decades (vehicles with gas engines of course) are equipped with detonation sensors, which is a piezo-electric sensor that generates a signal based on a "specific tuned frequency". When the PCM receives this signal which is pre-ignition or detonation, the timing is retarded to eliminate it.

Now, with all of this basic background stated in simple and generic terms, let's look at the effect of octane.

Higher octane (higher index number) gasoline has a higher resistance to pre-ignition or detonation. It is less flammable than lower octane fuel and thereby produces less BTU per pound. Using higher octane gasoline in vehicles that do not require it can lead to building carbon deposits in the cylinder and combustion chamber at a higher rate than what would happen with a lower octane gas.

In other words, if FMC says 87 octane is fine, then use 87 octane.

87 octane ethanol VS 87 octane pure gas.

Ethanol by nature has a much higher octane rating than gasoline, in fact the BTU per pound is roughly half of gasoline. Which explains why a race car on alcohol takes nearly 2 x the amount for the same horsepower.

All alcohol is hygroscopic (meaning it attracts moisture) and can become very corrosive by nature.

Alcohol at proper levels mixed with gasoline is approved by vehicle manufacturers, E-85 can only be used in vehicles specifically equipped to use it.

In the end, pure gas is the best thing to use if it is available in your area and within your budget. Most places around here (NC) get upwards of an additional $1 per gallon, which makes it not cost effective for vehicle use. However, I always used it in my boats and continue to use it in all of my small engines.
 
Dutch061 said:
Octane is an index number assigned to the resistance of fuel to "pre-ignite" meaning it lights before the ignition system starts it.

Pre-ignition or detonation occurs when the flame front collides with itself and is typically caused by hot spots (IE carbon deposits) within the cylinder or combustion chamber that starts the combustion process by more than the intended ignition source.

Everything built within the last 3 decades (vehicles with gas engines of course) are equipped with detonation sensors, which is a piezo-electric sensor that generates a signal based on a "specific tuned frequency". When the PCM receives this signal which is pre-ignition or detonation, the timing is retarded to eliminate it.

Now, with all of this basic background stated in simple and generic terms, let's look at the effect of octane.

Higher octane (higher index number) gasoline has a higher resistance to pre-ignition or detonation. It is less flammable than lower octane fuel and thereby produces less BTU per pound. Using higher octane gasoline in vehicles that do not require it can lead to building carbon deposits in the cylinder and combustion chamber at a higher rate than what would happen with a lower octane gas.

In other words, if FMC says 87 octane is fine, then use 87 octane.

87 octane ethanol VS 87 octane pure gas.

Ethanol by nature has a much higher octane rating than gasoline, in fact the BTU per pound is roughly half of gasoline. Which explains why a race car on alcohol takes nearly 2 x the amount for the same horsepower.

All alcohol is hygroscopic (meaning it attracts moisture) and can become very corrosive by nature.

Alcohol at proper levels mixed with gasoline is approved by vehicle manufacturers, E-85 can only be used in vehicles specifically equipped to use it.

In the end, pure gas is the best thing to use if it is available in your area and within your budget. Most places around here (NC) get upwards of an additional $1 per gallon, which makes it not cost effective for vehicle use. However, I always used it in my boats and continue to use it in all of my small engines.
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wow. This blew my mind. Thanks for the lesson.

I always put 91 in the truck (and everything else) thinking it’s better than 87 and not minding the additional cost.

Can you confirm that’s a bad idea?

Given this, why is it that other vehicles (eg my Volvo and Audi) recommend 91 in the manuals?
 
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