I'm sure this as been talked over a thousand times but I coulnd't find a thread in the search bar. I have a 5.0L and been running 87 octane with no issues. But, I wonder sometimes what, if any, does switching to 93 octane do for the 5.0L. What octane are you guys running on your 5.0L's and if you are running a higher octane (89,91,93), do you see/feel any difference?

 

There is no benefit in using higher octane gas on any car that has not been specifically tuned for it.

 

Well it doesn't help to wonder why Ford put "using a higher octane level will provide a increase in performance" in the manuals.

 

Most modern engines can produce a benefit with the use of higher octane fuel. Auto manufacturers are under competitive pressure to specify the least-expensive fuel as a requirement for non-luxury vehicles. As a result, you have engine management computers which retard timing and perform other adjustments to allow engines to safely operate on 87 octane, but may allow better performance with higher octane.

Whether the better performance is worth the cost may be debatable. In my experience with vehicles other than the F-150, the cost of premium octane fuel is often greater than the benefits provided. If 87 octane is recommended, that's probably what I'd stick with, and save some money at the pump.


JKG

 

90 is the best I can get here. That's what I run but I'm pulling a trailer a lot also. When you do the math it costs me an extra $2 per tank since I don't ever run it down to empty. I feel that it pulls a trailer better and were spending 20k+ on these trucks for a cheap one what's an extra $2 per week.

 

See, that is the same sort of thinking that I have. If you filled the truck up all they way (36 gallons), you will pay $7.20 more for that tank of gas assuming premium is $0.20 greater than regular. I can last easily 2 weeks on that one take of gas. So, $3.60 more a week is not a big difference to me. I think I am going to try putting premium in and see what different results I can get on MPG and performance.

 

High octane fuel ALWAYS has the POTENTIAL to make more power than the lower octane fuels . The compression ratio for the 4.6L is compatible with high octane fuel. I haven't looked at the compression ratios for the other Ford engines. The 4.6L I have "seems" to have more power with the higher octane fuels. I am saying "seems" because I have no dyno test results to show, and do not intend to pursue this issue. If the engine management system is up to the job,you are good to go, IMO.

 

in Canada using premium 91 octane fuel is the only way you get 100% gasoline and that's not even true of all the retailers.

The owner's manual words it that the computer will improve performance if higher octane is used. I am happy with the performance and economy I'm getting on 87 octane, but I do plan to try a full tank of 91 to see how the truck feels on higher octane gas.

 

The compression ratio of the 5.0L is 10.5:1 I believe. I think I have read somewhere that anything above a 10.0:1 compression ratio is considered a high compression ratio engine and performs better on premuim fuel.

 

Octane has zero to do with power. It makes no more power with 87 or 91 or 105. Octane is an additive added to fuel to reduce pre-ignition. Gasoline like diesel will ignite under compression without a spark however unlike diesel it is less predictable and will ignite more or less when it dam well pleases. So we add spark to ignite exactly when we want it too. However without octane added it is still going to ignite before you add the spark. So we add octane which lets the fuel go under higher compression before you add the spark to ignite it. As you advance the timing (add spark later) the fuel becomes more subseptable to pre-ignition as the compression gets closer to top dead center or after top dead center of the compression stroke. So more octane makes timing advancement further and prevents pre-ignition also refered to as enigne knock. Of course there is a point of diminishing returns you can only advance so far and then any further advancement you actually loose power and performance and fuel mileage. The flex fuel engines had the ability to use E85 Ethanol 105 Octane rating. So timing advancement is even further on those engines and probably the enigines that will actually see the most benefit from using 91 or 93 octane fuel as they have the greatest timing advance curve.....