Fuel Mileage

[mattman]

I feel that my mileage has gone down in the last month or so. Might be the winter fuel or the fact I have been filling at a different station. Will switch back to my old station and see what happens.

 

[Diamondpilot]

I do not see what is wrong towing at 75mph if the truck and trailer are in good shape. I tow about 10,000 miles per year and no issues. My neighbor does about 5,000 a year with a 5th wheel and probably another 20,000 towing his mowers all over for work. He never has any problems either, but we maintain our stuff.

Chris

 

[WH401]

#2 is close but not correct. Gasoline in an engine burns rapidly but doesn't explode normally. And both gasoline and Diesel engines can suffer mileage loss in winter. But a gas engine can also pick up HP due to increased fuel/air density.

When gasoline is outside of a compression chamber or a confined space, (a compression chamber could be the cylinder of an engine or a confined space could be a fuel tank), than yes, it just burns rapidly. But, when you place it inside the cylinder of an engine, (which has some sort of compression), and then it's ignited by a spark plug, it explodes. Have you ever tried to start a fire with gasoline?, when you throw the match on it, it just goes up in a huge ball of fire, much like in the same way you will if you were to actually try something like that. Have you ever watched a gasoline powered car catch on fire? what does the fuel tank eventually cause the car to do?, explode. Do you like those big explosions you see in Hollywood movies these days?, most of them are just simple containers of gasoline rigged to a simple ignition system.

An interesting way to see the combustion of gasoline while it occurs inside an engine is to attach a piece of thick plexi-glass to a worn out, low compression, 2 stroke engine, equipped with a horizontal spark plug. This will allow you to watch the explosion of gasoline as it happens, and even though that probably isn't OSHA approved, it's definitely a neat thing to see in person.

Yes, both diesel and gasoline engines can suffer mileage loss in cold weather, though I only mentioned diesel fuel because the OP's truck is diesel powered. Yes, gasoline engines can experience an increase in HP from an increased air/fuel density. Unfortunately though, unless you are able to increase the amount of air being fed to a gasoline engine, such as by turbo charging, the increase in hp from just simply a denser air/fuel mixture is marginal at best. Gasoline engines by nature are manipulated by air, where as diesel's are manipulated by fuel. This is why it's very easy to add lots of power to a diesel engine. Depending on the injection system, whether mechanical or electronic, it's just a simple matter of turning a screw or pushing a few buttons on an electronic programmer.

 

[Ryan03]

One thing to look at is winter fuel, it just doesn't burn with the higher amount MPG that you'll attain from summer fuel.

Secondly, the air filter change is a good point. In my 06' Dodge, I changed the air filter at 25k, even though the "minder" was barely off being perfect. Here's what it looked like, and what it looked liked compared to the new one:


I don't do any kind of serious off-roading, other than living on a 1/4 mile driveway, and you can see how nasty that thing looks. After changing the filter, I was instantly noticing an increase of .5 - 1.0 mpg at the pump, and easier turbo spool up.

I did not read every post, so I apoligize if this has been mentioned already. The most likely cause of the nasty filter is long term idling in cold conditions. I see this on my Dmax in the winter monthes when I warm it up regularly at work on fast idle. The truck will draw in a portion of its exhaust through the intake tract, contaminating the filter with oily soot.

 

[Ryan03]

I do not see what is wrong towing at 75mph if the truck and trailer are in good shape. I tow about 10,000 miles per year and no issues. My neighbor does about 5,000 a year with a 5th wheel and probably another 20,000 towing his mowers all over for work. He never has any problems either, but we maintain our stuff.

Chris

Neither do I. 70 to 75 MPH is my normal towing pace on the freeway in ideal weather and traffic conditions. My truck and trailer are also regularly maintained and in impecable mechanical condition.

 

[WH401]

I did not read every post, so I apoligize if this has been mentioned already. The most likely cause of the nasty filter is long term idling in cold conditions. I see this on my Dmax in the winter monthes when I warm it up regularly at work on fast idle. The truck will draw in a portion of its exhaust through the intake tract, contaminating the filter with oily soot.

While I agree with you that long term idling could cause an oily filter, it wouldn't be that as I try to keep from idling as little as possible. Whenever I come to a stop, say waiting to pick someone up from school, I always cut it off. On cold mornings I'm able to plug it in, and I only let it idle enough to build oil pressure and then I'm on my way. The only time I might let it idle is if it's been sitting all day in below freezing weather, but even then it would only be for about a minute with the Jake on, and those times are few and far between.

 

[FlaDon]

When gasoline is outside of a compression chamber or a confined space, (a compression chamber could be the cylinder of an engine or a confined space could be a fuel tank), than yes, it just burns rapidly. But, when you place it inside the cylinder of an engine, (which has some sort of compression), and then it's ignited by a spark plug, it explodes. Have you ever tried to start a fire with gasoline?, when you throw the match on it, it just goes up in a huge ball of fire, much like in the same way you will if you were to actually try something like that. Have you ever watched a gasoline powered car catch on fire? what does the fuel tank eventually cause the car to do?, explode. Do you like those big explosions you see in Hollywood movies these days?, most of them are just simple containers of gasoline rigged to a simple ignition system.

An interesting way to see the combustion of gasoline while it occurs inside an engine is to attach a piece of thick plexi-glass to a worn out, low compression, 2 stroke engine, equipped with a horizontal spark plug. This will allow you to watch the explosion of gasoline as it happens, and even though that probably isn't OSHA approved, it's definitely a neat thing to see in person.

Yes, both diesel and gasoline engines can suffer mileage loss in cold weather, though I only mentioned diesel fuel because the OP's truck is diesel powered. Yes, gasoline engines can experience an increase in HP from an increased air/fuel density. Unfortunately though, unless you are able to increase the amount of air being fed to a gasoline engine, such as by turbo charging, the increase in hp from just simply a denser air/fuel mixture is marginal at best. Gasoline engines by nature are manipulated by air, where as diesel's are manipulated by fuel. This is why it's very easy to add lots of power to a diesel engine. Depending on the injection system, whether mechanical or electronic, it's just a simple matter of turning a screw or pushing a few buttons on an electronic programmer.

High speed cameras have been used to film gasoline in an engine from the point of combustion and proven that it is not an explosion. An explosion is an uncontrolled burning of fuel while an engine is a very controlled burning of the fuel. It is a buildup of pressure along a rapidly moving flame fronts that are controlled by such things as piston domes and combustion chamber designs in the heads. Gas tanks explode because the pressure and liquid is contained until rupture and the exposed to air in a large volume of heated vapors. The term for that tank explosion is a BLEVE. Boiling Liquid Expanding Vapour Explosion It is the rapid expansion of the liquid to a vapor that causes it. The same thing as happens in a boiler explosion when water turns to steam.

 

[FlaDon]

I do not see what is wrong towing at 75mph if the truck and trailer are in good shape. I tow about 10,000 miles per year and no issues. My neighbor does about 5,000 a year with a 5th wheel and probably another 20,000 towing his mowers all over for work. He never has any problems either, but we maintain our stuff.

Chris

If you maintain your equipment and don't go cheap, there is no reason you can't tow at whatever the speed limit is. Or in some cases over the limit by 10 to 15 MPH. Pleads guilty to running at 80 in a 65 zone while towing.

 

[RobertN]

I pulled my 5th wheel at 70mph in Texas, at the speed limit. Towed and handled excellent. I backed down to about 62mph, because my fuel mileage took a dump, not because of how the trailer handled. Trailer is in good shape though. New tires, good brakes, freshly greased bearings.

Have had my flatbed trailer with tractor at 75mph for a short distance. Same; good condition, good tires, good brakes, balanced load. Handled like a dream.

But, that is why I tow with a 3/4 ton, and am well within the limits of truck and trailer weight and capacity wise.

For the most part it does not matter for me though... Towing speed limit in Calif is 55mph. Sucks when your running I-5 thru the middle of the state and cars are whizzing past. I think the Calif regs are dangerous... Cars going 70+, Class-A+B trucks, as well as pickup/cars towing, going 55mph. Too much of a speed mismatch, especially when you try to pass in a slower towing vehicle.

The other thing is, on 65mph 2 lane, when you are towing at 55mph. Sucks... Especially when there are no good places to pull off, or people do not let you merge back in from turnouts...

BTW, I think you're NUTS driving at those speeds, lightly loaded or not.
A trailer is basically a very unstable appendage to a truck.
THIS should be FIRST OF ALL !!! Your ignorance of seasonal fuel is a trivial non-issue.

I wouldn't care, but for the fact that other people are on the road - and I'm ONE of them.

 

[VitaBene]

Winter Fuel costs me 1.5 plus MPG in my 99 F250 w/7.3 diesel. I hand calculate everytime I fill up and can always tell when the winter fuel comes in.

There is no question that you will get far superior mileage towing at 60 MPH as opposed to 70 MPH but towing the speed limit with good equipment is safe and prudent. The brakes on my well maintained trailer are as good or better than the brakes on the pickup.