Diesel Fuel

[JIM KELLER]

Inside my fuel door is a sign that states ; Diesel Fuel, #1 preferred, #2 accepted. Does everyone know the difference between #1 and #2 ? Wouldn't you like to give it a drink of what it prefers once in a while !

[Orren Zook]

Diesel fuels are classified 1D, 2D, and 4D. Low speed, stationary units use 4D fuels. 4D fuel is not appropriate for most mobile equipment. On-highway and mobile equipment use 1D and 2D fuels. High speed diesel engines use either 1D or 2D fuels. Important characteristics of diesel fuels are its viscosity, pour point, and cetane number. The primary differences between 1D and 2D fuel are the pour point and the viscosity. Pour point is the lowest temperature at which a liquid will flow. Viscosity is the resistance of a liquid to flow. A 1D fuel is designed for cold weather operation; thus, it is less viscous and has a lower pour point. A 2D fuel is used in warmer weather because it has a higher viscosity and pour point. The higher viscosity provides better lubrication qualities for the moving parts of the fuel injection system. Because 2D fuels contain more Btu's (British thermal units - the amount of heat necessary to raise one (1) pound of water one (1) degree fahrenheit) per gallon, they are able to deliver more power per gallon. This is critical to diesel engine fuel economy. The higher the Btu rating a diesel fuel has, the greater power yield per gallon; thus, higher mpg will result. Cetane rating is the diesel equivalent to gasoline's octane rating. Unlike an octane rating, which rates gasoline's resistance to spontaneous ignition, the cetane rating number (usually 40 to 55 for medium to high speed engines) notes the relative ease with which diesel fuel ignites. The higher the cetane number, the easier the fuel ignites; the higher the octane number, the more resistant the fuel is to ignition. Each manufacturer usually specifies a minimum or maximum cetane rating and the suggested operating temperature for 1D and 2D fuels. A given fuel may meet 1D or 2D specifications, but if the Btu rating is too low, then decreased fuel mpg will result.

[BrianE]

Jim,

Since you're in the business, is this a test? :rolleyes:

With the advent of ULSD (Ultra Low Sulfer Diesel) the lubricity and economy characteristics of diesel have changed significantly. Would suggest contacting Prevost for a more recent recommendation as to the preferred fuel.

The following is a FAQ copied from the Exxon website:
Why shouldn’t I just use Diesel Fuel No. 1?
While Diesel Fuel No. 1 has an advantage in low temperature operability, there are some disadvantages, as well. The energy content of Diesel Fuel No. 1 is about 95% that of Diesel Fuel No. 2 and will provide a correspondingly lower fuel economy. Diesel Fuel No. 1 is also lower in viscosity and provides less lubrication for the fuel pump and fuel distributor.

[truk4u]

Back in the old days, number 1 was heating oil and number 2 was for engines. There were no road taxes on number 1 and many used the home heating oil in their trucks because it was cheap.:rolleyes:

Always wondered why our garage furnace used so much fuel!:eek:

Remember the Oil Embargo?

[Kenneth Brewer]

Jim,

Since you're in the business, is this a test? :rolleyes:

With the advent of ULSD (Ultra Low Sulfer Diesel) the lubricity and economy characteristics of diesel have changed significantly. Would suggest contacting Prevost for a more recent recommendation as to the preferred fuel.

The following is a FAQ copied from the Exxon website:

Here in the south, I have found it rather rare to have #1 fuel at the pumps anyway.

[Orren Zook]

You've also got the DOT checking fuel for dye - with that big Racor displaying your fuel color it's pretty easy to see if you've been running kerosene or heating oil.

[rahangman]

SO, for a poor Northwestern Kid without his degree in Engineering, what is the Official "Told you so" from the POGs.....For my 1989 chassis 8V92T which seems to be running (140K miles) virtually flawlessly (hope I don't jinx it), it seems to me that I should stick with #2 most of the time, unless when in Colorado, (next week) and then, if not #1 , just add the Cetane additive. Hmmmm:rolleyes:

[Orren Zook]

SO, for a poor Northwestern Kid without his degree in Engineering, what is the Official "Told you so" from the POGs.....For my 1989 chassis 8V92T which seems to be running (140K miles) virtually flawlessly (hope I don't jinx it), it seems to me that I should stick with #2 most of the time, unless when in Colorado, (next week) and then, if not #1 , just add the Cetane additive. Hmmmm:rolleyes:

I'm thinking that this time of year an anti-gel or flow improver additives would be more in order for travel in winter climates.

[JIM KELLER]

Good job Brian and Orren. I'm sure some of POG Members just learned a lot about Diesel Fuel.

[Jon Wehrenberg]

SO, for a poor Northwestern Kid without his degree in Engineering, what is the Official "Told you so" from the POGs.....For my 1989 chassis 8V92T which seems to be running (140K miles) virtually flawlessly (hope I don't jinx it), it seems to me that I should stick with #2 most of the time, unless when in Colorado, (next week) and then, if not #1 , just add the Cetane additive. Hmmmm:rolleyes:


I am not sure we need to ever add anything. Having said that I don't think it would be wise to fill up in FL and then go into sub zero temps without filling at a truck stop located in the area of cold temps.

With EPA regulations I don't know if fuel is adjusted for the season anymore, but at one time fuel purchased in northern areas was adjusted to prevent such conditions such as gelling in the winter.

FWIW I have never put any additive in the fuel in my coach and we have run in temperature extremes ranging from 100+ to minus 26 F. (Not on the same day.) The time we were in the sub zero temps we were returning from FL and had FL fuel on board but when we stopped in WV for the night in the -26F temps we never shut the bus off, but left it on high idle while we slept.

We froze while driving because of cold air spilling off the windshield, but the fuel never gelled.

[rahangman]

Thanx for the replies....we have spent some time in Ohio with -25 wind chill overnight 3 nights in succession, slightly warmer during day but did not leave the bus running. Did however use the Webasto extensively and "got away with it", yup, cold driving, and don't care to go into that kind of weather anymore. :D

[Jon Wehrenberg]

Your engine and fuel doesn't care about wind chill.

But when the actual temperature starts to submarine your engine, fuel and bus will not function in the manner you have been used to.

[Kenneth Brewer]

Your engine and fuel doesn't care about wind chill.

But when the actual temperature starts to submarine your engine, fuel and bus will not function in the manner you have been used to.

Thank you for that. On a running diesel, a portion of the fuel is returned to the fuel tank; it is warmed by the engine and by the Racor if it has auto-heating (normally comes on about 39 degrees or so) and thereby warms the fuel in the tank. If the Webasto is running and keeping the bays warm, that is good.

If the engine is shut down and the Webasto as well and/or no (sufficient) bay heat, and the fuel temperature drops to ambient or near ambient (subzero) before attempting to start/run, gelling will have begun. Once that happens, your troubles have begun as well. And this is with #1 diesel. Additionally, if there is no bay heat, even with a running generator, fuel freeze can and does often occur and the generator can die. It should be determined (I haven't done this yet, either) whether the generator fuel comes through the Racor (w/heat element) or other auto-heating fuel filter/dewater system in our Prevost.

Fuel freeze can occur with a running bus if it is cold enough, which is why bus companies mix kerosene in diesel for as much prevention as they can get, based on their experience. I have heard that a ratio of 1 in 10 gallons is common. I know only a bit about freezing fuel because it occurred twice to me. Once you have lost the ability to start/run the main engine, and the generator, you may/probably(?) lose the Webasto too.

[Denny]

I have been told at Flying J and other truck stops that the fuel is adjusted according to the outside weather. All the more reason to be careful of buying fuel in the South and coming into a cold climate. I don't like to rely on someone else winterizing the fuel. Could be they are having a bad day and everyone else has to suffer with them.

I add my own anti-gel to the bus. I feel it gives added protection.

[Orren Zook]

Denny, let's test that theory with a trip to a warmer climate in the next couple of weeks... I heard that you've got some spare time now.

[Denny]

Orren,
I'm sitting here watching it snow and asking "why am I still here?" Oh well in a couple of months the noose should be completely off of my neck. Now I am playing catch-up on all the on going projects - honeydo list, rental properties, bus maintenance, etc.