Worsc MPH with Power Service??

[GreatWhitehunter]

Well, after reading alot of pro's and con's on additives for USLD I decided to give it a try. I was heading on a 1000 mile trip to northern Maine. So I filled up and added Power Service. Around 500 mile in I checked MPG. And I actually lost 3/10's of a mile. I was shocked. I filled up again and drove another 500 miles with no change. I repeated the process on the 1k miles home and and the same results. It's been two weeks with just daily driving and no Power service and still my MPG hasn't moved. What gives? Has anyone else had this issue? Is it perhaps a coinsidence that this happened and maybe it's just bad USLD in the New England area?

Matt T.

 

[DieselPower]

Could be any number of thing's. To start it wasn't a big MPG change. You could have been getting winter blended fuel that is a mix of ULSD #2 and either ULSD #1 or ULSK #1. These winter blends alway's show lower fuel economy and lower power. ULSD #1 and ULSK #1 both produce less energy per gallon than ULSD #2 alone. The farther north you get the greater likelyhood that you got a winter blend and Maine's prety far north.

Were you hauling anything extra to add to the vehicles weight or aerodynamic's?

Driving faster than normal? The faster you drive the lower your MPG.

It's really hard to calculate MPG's in the 1/10's since there are so many varriables that can effect it. If you had said it dropped 2 or 3 MPG then that would be a problem.

 

[GreatWhitehunter]

I was thinking the same thing in reguards to the winter blending. NE had just begun a deep freeze. I did have a little extra weight but nothing substanial.
My concern is that the lost MPG hasn't returned.

Matt T.

 

[Rusty]

My concern is that the lost MPG hasn't returned.

Matt T.

Have you changed tires or tire pressure?

 

[GarthH]

One of the big factors I have with fuel economy is the altitude (or is that attitude). I often drive to a city just south of us and find that my fuel economy is much better going than coming back. Using MS Streets & Trips I noticed that the altitude change is 700 feet.

Garth

 

[GreatWhitehunter]

Nothing has changed except the power service. No tire pressure and anything, thats why it's so mind boggling.

Matt T.

 

[scagwildcat]

GREAT,
im in CT. and my f-350 does the same thing in the winter, with power service, wait till the middle of April, mpg's will go up.

 

[cp1969]

It isn't the Powerservice unless you are using LOTS of it. You are in all liklihood seeing the effects of blended fuel. It will go away when the weather warms up and blended fuel disappears.

Most additives are composed of combustible fluids (#1 diesel mostly, with petroleum distillates, naptha, and xylene; aka #1 fuel oil, lighter fluid, and paint thinner), all of which will at least burn in a diesel. So, depending upon the BTU value of this cocktail, you might get an increase in mileage, if for no other reason than you are replacing a volume of diesel fuel with the same volume of additive you choose to pour into the tank. Consider this example:

A vehicle has a ten gallon tank. Using #2 diesel, the operator find he can travel 200 miles before he runs out of fuel, for a calculated mileage of 20mpg.

Operator tries adding one gallon of additive on next tank, then fills with 9 gallons of fuel. Again, he travels 200 miles before it runs out of fuel. What is the fuel mileage now? Miles travelled is the same but what number do we use for gallons of fuel burned? Nine or ten? The operator didn't put in ten gallons of #2, but ten gallons of "fuel" got burned. If he leaves the additive out of the calculation and uses the nine gallon figure from his sales slip, he will get 22.22 as a new mileage figure. It would appear that a mpg increase on the order of 10 percent was realized when in fact no change at all occurred.

This example assumed the BTU values for the two constituents was the same when in reality they are not. I would guess additives' BTU value is less than #2 simply because they are composed mostly of #1 fuel oil and this would cause fuel mileage to go down slightly, maybe up to 5% or so. You could run a full tank of PS or a 50/50 mix or any other proportion you desire and my guess is in every case you would see a decrease in efficiency simply because you are burning a high concentration of #1 fuel oil.

There are many other reasons people use additives; lubricity, cetane increase, water emulsification, water demulsification, etc. But changing the efficiency of an engine isn't really in the cards for additives. If cetane is below the minimum required for the engine, that might be the only case. But increasing cetane is not a case of 'more is always better.' If the fuel is above the minimum cetane required for the engine, raising it won't help a bit, in fact it might hurt.

 

[GreatWhitehunter]

Thanks for the well thought out and explained answers. I was pretty shocked today as I picked up a dump trailer. Towed it (empty) from NH to CT on the Highway (65mph) and my MPG didn't move at all. It stays at 16.7 loaded or unloaded. I'm beginning to believe 100% that the power service was not the cause. I add the PS due to the info I've read about the low lubricity of the USLD. I didn't really add it to improve MPG but I didn't expect to loose MPG ( not that it really moved, it decreased 2/10 ) But I wanted to make sure I wasn't doing anything wrong since this is my first diesel engine.

Matt T.

 

[LarryRB]

I have an 06 Dodge, had an 01 before that, and many tractor trailers before going back to 74. I always use Howes Lubricanteven in my Kubota. This new Dodge is the first one that mileage is varying... 16 to 18.4. depending on the day.. The 01 was pretty much locked in at 18. Neither did well when towing my tractor., especially if I have to negotiate Bigelow Hollow hills.