Does anyone know why Ford doesn't recommend anything more than 87 octane for the 2011 Ranger 4.0? I like to run a tankful of premium every once in a while to keep things clean but the owner's manual advises against it.

 

The computer is set for regular fuel octane. Regular fuel cleans the engine just the same as premium. Running premium only makes you feel better, it does nothing for the truck.

 

My 98 Ranger (3.0, 5 speed, 2 wheel drive) gets 4 miles per gallon better with hi-test. It also doesn't spark knock and it pulls the hills in a higher gear with hi-test gas. I have 237,500 miles on it now and have been running hi-test since I bought it (83,000 miles) Some people think that I am crazy but the figures don't lie.

 

Before running premium, ask yourself some questions.

Does this car have a turbocharger or supercharger? (NO)

Does this car have a higher than normal compression ratio (NO)

Does this car have a custom tune that uses more aggressive timing curves (NO)

If the answer to any of the above is yes, then go ahead and use premium. If all the above are NO, then use what the manufacturer recommends.

Octane does not refer to the quality of the fuel, it refers to its resistance to ignition prematurely and spontaneously exploding. The higher the octane, the harder it is to burn. Engines that have any of the above mentioned features or equipment require higher octane fuel because those kinds of modifications can cause pinging or detonation which can cause engine damage, and the higher octane helps overcome those issues.

The regular gasoline has the same detergents and add pack as the premium. So both engines will clean your engine just as well.

So what would be the downsides to burning premium(91 or 93) in your engine instead of regular 87? Well, decreased performance for starters (the fuel burns more slowly, since your engine is not designed for that, it cannot properly harness it), decreased fuel economy (again, the engine was not designed for it), increased carbon build up (the exact problem you were trying to avoid, the fuels increased resistance to burning causes more unburned carbon deposits which remain in your engine), increased emissions (the fuel takes longer to burn which means more unburned fuel enters the exhaust The catalytic converter helps clean it up the increased emissions but the catalytic converter was not designed for the increased workload), and wasted money (it obviously costs more, and your engine simply cannot harness it),

So in simply summary, your car was designed to achieve optimum performance, fuel economy, and emissions using the fuel the factory designed it to use. The owners manual says use 87, thats what you should use, and now you know why you shouldn't use something higher.

 

^+1 on ranger pats post about Not using premium fuel in our Rangers.

Ford advises against regular use of high octane fuel because the engine compression, valve & spark timing aren't designed to make the best use of higher than 87 octane & over time it can cause excessive combustion chamber deposit loading.

The higher octane fuel is more difficult to ignite, so using it in an engine not designed to use it, is sorta like running with delayed/retarded spark & wrong valve timing, as the spark isn't advanced enough to begin optimum combustion & the exhaust valve is opening for the exhaust stroke while the fuel is still burning. So that combustion temp is lost/dumped & not used to push the piston down on the power stroke, thus we don't get full advantage of the BTU content of premium fuel.

Ford says if we use it continuously, the unburned fuel can add to the combustion chamber deposit loding & that can cause preignition/spark knock problems.

It can cause the head exhaust port, exhaust valve & manafold, down pipe have to deal with higher temps from the fuel burning there & the cat converter runs hotter having to process the unburned fuel that gets to it.

So no advantage to using premium fuel in a low compression clean engine not designed for it.

Maybe the reason Dan Robertson gets better response using premium, is because of combustion chamber deposit loading causing higher compression, so he needs to use higher octane fuel so his engine won't suffer preignition/spark knock.
His spark & valve timing still arent optomized to make optimum use of premium, unless he has messed with compression, spark & valve timing.

 

The reason that I started running hi test was because my truck was spark knocking in over drive whenever I was traveling 50 MPH or less (especially on the hills) and on certain longer hills I had to shift down to 4th gear. My grandfather used to run high test gas in an old Farmall tractor during the fall when he used it to dig potatoes. It wouldnt haul the digger in 2nd gear with regular but would with high test. He passed away in 1978 and I still have his old tractor. I dont farm potatoes but I do plow snow. The tractor will not plow snow in 3rd gear with regular gas but it will with high test. (2nd doesn't give enough ground speed to cast the snow away but 3rd does) I know that my truck is a different situation than the tractor as it is controlled by a computer. My truck will pull the same long hills in 5th gear when using high test and there is no spark knocking what so ever. I have been running high test for roughly 154,500 miles with no engine problems at all. I service it religiously and it still doesn't burn any oil at all. I have switched back numerous times and every time that I do, my mileage decreases by about 4 mph and it starts spark knocking almost immediately. I even disconnected the battery over night once prior to running a fresh full tank of regular gas. I was hoping that it would have to learn how to run again with regular gas but it never did. I also have a 2005 Ford Escape with a 3.0 and an automatic transmission. The high test makes seems to make no difference in that vehicle at all and it doesn't spark knock so I use regular gas in that one. The extra cost of the high test and the added mileage almost equal themselves out but not quite. It does cost me a few pennies per mile more with the high test.

 

Dan if you have any pending or set trouble codes, they might offer up some clues to whats going on, as it isn't normal for our engines to require premium fuel
.
Otherwise things like, a vacuum leak & this would include a stuck open PCV valve, or cracked/dryrotted leaking hose or connection to it, intake manafold gasket leak, low fuel pressure from a clogged fuel filter, crimped/kinked fuel line, or weak fuel pump, clogged fuel injector sintered filter or dirty injectors causing a lean squirt, dirty MAF sensor, lazy O2 sensors, wrong heat range spark plugs, combustion chamber deposits, messed up ignition timing, or some combination there-of should be on your suspect list.

If you suspect dirty fuel injectors or combustion chamber deposits, maybe consider a dose or two of the 20oz Techron Concentrate Plus at the pump so you get good mixing, before filling up with Chevron, Texaco, CalTex, or now Shell, all of which have some PEA in their fuel ad pack, which along with the Techron will raise the treat rate 10X above pump gas alone, then doing some spirited daily driving with rpm above 3600 for 2-3 miles as prescribed by Ford in their 4.0L decarb TSB, might tidy things up enough for you to get back to using 87 octane. Techron for the old tractor might help too!!!

Some engine ping thoughts for pondering.

 

It looks like the bottom line is personal preference. I'm not planning on running hi test very often but was curious to know if it would hurt. I haven't encountered it lately but there have been times where my gas station has been out of regular and I've had to buy the hi test. That happened a couple of years ago, when I still had my Honda and it actually ran better on 93 even though the fuel door said 87 octane was fine. I towed a 4000 lb flat nose enclosed trailer back in the summer when I moved. I started out with 87 in the tank but stopped and filled up with 93 for the pull up the long mountain. It seemed to pull harder on the hi test than what I'd seen with regular but that's just a seat of the pants opinion. Octane didn't matter though as my towing mpg was only about 10 mpg with the load behind me. I've got the factory tow package on this truck.

 

Uhm, no bottom line is not personal preference, you engine will gruadually get runied if you use the high octane. If your truck is pinging on the octane it is designed to use, something is wrong. You likely have a vacuum leak, which causes a lean mixture which will ping. The delayed burn issue caused by high octane, as described, will ruin your expensive catalytic converters. And yes, it will overheat the valves, which can cause them to warp and fail.

What you need to do is have the fuel trims checked out to see if it is running lean, find and correct any vacuum leaks, clean the injectors, run a product like Seafoam through your engine to remove any existing carbon deposits. That should make the pinging problem you are having go away.

Comparing your car to a Honda has nothing to do with anything. Hondas are designed to run on 91 or 93 gas, and then with the addition of a knock sensor and the VTEC system, can detune themselves to run on a lower octane without pinging or damage. Your engine was designed to run on 87, and does not have any technologies or features to allow it to uptune to use a higher octane.

 

Its my truck and my money and after I pay for it, its my gas so I would say that makes it personal preference. The 237,500 trouble free miles speaks for itself.

 

Hence thats why it pings now.

I have put many many more miles than that on engines.

Call it preference, its your truck its true, but the reality is it ruins things. If putting a higher octane fuel was OK, then Ford never would have issued a TSB instructing owners NOT TO DO IT, and they never would have introduced their own private label decarbon treatment to remove carbon deposits for 4.0L V6 engines that have developed excessive carbon deposits from putting a higher than recommended octane fuel.

My 4.0L sees much harder use than yours, and has no carbon deposits, no pinging issues, and has comparable mileage to yours.

Preference is where you have two or more choices and it doesn't matter which one you choose other than your liking. Personal preference does not change the reality. The reality is according to your descriptions, your engine currently pings not because it has run 237,000 trouble free miles, but that it still runs despite its troubles. It has suffered excessive carbon build up from either running rich or from too high an octane, it probably have multiple vacuum leaks. If your engine were to be dismantled, chances are you will find not one or two valves exhaust receded into the head, but all of them. This is from excessive heat. I've seen it enough times to know.

Sure the engine will still run, but it will not produce its original power, fuel economy, and it will not meet like new emissions standards. So not only are you wasting fuel, but you are voluntarily wasting the more expensive premium fuel that is really offered for those of us that actually have cars that need high octane fuel.

 

Yup, if it's knocking on 87 Octane, then something is wrong. 3.0s are lame enough engines that they could probably run on 85 Octane just fine.

 

When my truck quits running I'll be sure to let let you know.

 

Dan, have you compared your fuel cost per mile using premium compared to regular? You state that you gain 4 mpg with the premium. considering the price differential - usually 20 cents per gallon more for premium around where I live. Is it worth it?

 

In one of my earlier posts on this thread I mentioned that it almost pays for itself. It costs me between 2 and 3 cents per mile more to burn hi-test. For that 2 or 3 cents, I get a quieter running engine that has more power on the hills. I've owned the truck for 10 years and I have put 155,000 of the miles on it myself. (it turned over to 238,000 last night) I'm 55 years old and don't need a power house. My lame 3.0 is just about bullet proof and gets me from A to B. Maybe something is wrong with it but if there is, it has been wrong for 10 years and 155,000 miles and the hi-test gas hasn't had an negative effects, only positive ones. In case anyone is wondering, my truck spark knocks on mid grade gas too (89 octane up here in Northern Maine)