Go Back   iRV2 Forums > MOTORHOME FORUMS > Class A Motorhome Discussions
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
 
Thread Tools Search this Thread Display Modes
 
Old 08-15-2009, 12:33 PM   #1
Junior Member
 
Join Date: Aug 2009
Posts: 3
Question Diesel fuel mileage and additives

I bought a new 2008 Allegro Bay 37QDB, Freightliner chassis, Cummins ISB 6.7L. 6speed Allison Tranny in March of 2009. The first 1000 miles pulling a 4200 lb jeep, at 62mph average, 100psi in the tire, average load, I averaged 8.7 mpg. Driving in the Rocky mountains with 4200 miles on it I was not overly impressed with the power. This is my first diesel and I have read a lot of discussions and ads on fuel additives to clean up the diesel fuel, lubricate the injectors, prevent freeze up, boost cetane, etc. Has anyone had any experience in performance or mileage improvement using additives? Will my performance improve as my engine gets broken in? Should I change out the primary and/or WIF filters, thinking they may be clogged from sitting on a dealers lot for a lengthly period, thus resulting in poor mileage? Thanks.
__________________

__________________
Hat2k
2008 Allegro Bay
Cummins 340 FRED
sleprr is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 08-15-2009, 01:08 PM   #2
Senior Member
 
wagon217's Avatar
 
Join Date: Jul 2008
Location: Lake Mary, Fl.
Posts: 161
I don't think that is bad fuel mileage at all for the miles you have on the engine. I would NOT use additives to your fuel as if you do a bit of researching on the Cummings site I think you will find that they recommend NOT using additives. My recommendation, filler up and enjoy the trip.
__________________

__________________
wagon217 is offline   Reply With Quote
Old 08-15-2009, 01:47 PM   #3
Junior Member
 
LargCarPilot's Avatar
 
Monaco Owners Club
Join Date: Jul 2009
Posts: 11
Send a message via Yahoo to LargCarPilot
I have owned/operated diesels for 30+ years in the transportation industry. I have probably (at one time or another) tried every product available on the market. I.E. Howe's, Lucas, etc. I have been using a product from Scheaffer's for the last 7 years and had a significant reduction in injector and fuel system problems. I am currently operating a large bore Caterpillar out putting over 900 horsepower to the rear wheels. Fuel system operation ranks high on my list of priorities!

Schaeffer Oil | Diesel Fuel Additives, Conditioners, Treatments
__________________
2001 Monaco Dynasty
"The hottest places in Hell are reserved for those who in time of great moral crises maintain their neutrality" -Dante
LargCarPilot is offline   Reply With Quote
Old 08-15-2009, 04:39 PM   #4
Senior Member
 
Elkhartjim's Avatar


 
Newmar Owners Club
Texas Boomers Club
Freightliner Owners Club
Join Date: Jul 2008
Location: Don't mess with Texas
Posts: 3,116
8.7 is darn good IMHO. Cummins recommends you not use any additives.
__________________
Jim with Judy
2017 Newmar Ventana 4369, 2005 Jeep Wrangler (Rock Crawler), 2016 Jeep Wrangler (Mall Crawler)
Elkhartjim is offline   Reply With Quote
Old 08-15-2009, 04:53 PM   #5
Junior Member
 
Join Date: Aug 2009
Posts: 3
My owners manual says do not use additives in the oil and says nothing about fuel additives. Cummins has a site which identifies several additives and their advantages according to Cummins. The site is cummins fuel additives
__________________
Hat2k
2008 Allegro Bay
Cummins 340 FRED
sleprr is offline   Reply With Quote
Old 08-15-2009, 05:19 PM   #6
Moderator Emeritus
 
Gary RVRoamer's Avatar


 
Join Date: Jan 2000
Location: Silver Springs, FL. USA
Posts: 18,085
The ISB is not a large engine for that size coach, so it is not surprising it does not impress you with its power. An ISC or even an ISL would be more appropriate to that size/weight, but would have upped the price quite a bit. Owners with somewhat smaller rigs and that engine are seeing 10+ mpg consistently.

If you find a fuel additive that somehow manages to increase the energy per gallon of diesel, the world will beat a path to your door and you will be a wealthy man. Good luck in your search!
__________________
Gary Brinck
Former owner of 2004 American Tradition
Home is in the Ocala Nat'l Forest near Ocala, FL
Summers in Black Mountain, NC
Gary RVRoamer is offline   Reply With Quote
Old 08-15-2009, 05:43 PM   #7
Senior Member
 
PizzaGuy's Avatar
 
Monaco Owners Club
Join Date: Aug 2008
Location: Lompoc CA
Posts: 137
If I got 8.7 I would have a party. My ISL 400 gets just under 8.
__________________
Don & Carol Croner, FMCA- F401447
2007 Monaco Diplomat PDQ 40
2007 Saturn Vue, US Gear Tow Brake
PizzaGuy is offline   Reply With Quote
Old 08-15-2009, 06:07 PM   #8
Senior Member
 
Eddie Foy's Avatar
 
Join Date: Jun 2008
Posts: 279
Shoulda bought a Mercedes. My 07 Presidio 39D with MBE 926 gets 10.5.
__________________
2007 Presidio 39D

Mercedes MBE 926
Eddie Foy is offline   Reply With Quote
Old 08-16-2009, 06:55 AM   #9
Senior Member
 
Elkhartjim's Avatar


 
Newmar Owners Club
Texas Boomers Club
Freightliner Owners Club
Join Date: Jul 2008
Location: Don't mess with Texas
Posts: 3,116
Quote:
Originally Posted by Elkhartjim View Post
8.7 is darn good IMHO. Cummins recommends you not use any additives.
My bad. The whole time I'm reading this I'm thinking oil.
__________________
Jim with Judy
2017 Newmar Ventana 4369, 2005 Jeep Wrangler (Rock Crawler), 2016 Jeep Wrangler (Mall Crawler)
Elkhartjim is offline   Reply With Quote
Old 08-16-2009, 08:47 AM   #10
Senior Member
 
Korryp's Avatar
 
Fleetwood Owners Club
Freightliner Owners Club
Join Date: Feb 2008
Location: Sammamish, WA
Posts: 159
My local Cat dealer who does only work and no sales of fuel additives mentioned that he has seen fewer problems with rigs that use Stanadyne in every other fuel fill up.
__________________
'07 Fleetwood Bounder Diesel 38N
Brazel's added: MP-8, Aero Muffler, Koni FSD Shocks, Bell Crank and Comfort Ride Control Valves. '08 Ford Escape Hybrid, Brakemaster 9100
Korryp is offline   Reply With Quote
Old 08-17-2009, 08:45 PM   #11
Junior Member
 
Join Date: Aug 2009
Posts: 1
I have a 1993 pusher 32 ft 5.9 slightly overloaded mechanical Cummins and the lowest mileage I have clocked was 8.5, with a fuel leak in the bottom of the tank, since repaired. I also drop to about 15 mph climbing all mountains, which is ok since all the Big trucks are right with me.
It is true that in the beginning of an engines life its efficiency is less while it is breaking in, after break-in it should improve slightly but do not expect a huge difference. The power and torque on a 6.7 B is similar to my 5.9, increases were required to get around emission laws. You have the added issue of that coach being a front engine diesel (I think) instead of a pusher, if so it has and will continue to have all the issues that a A gas coach has.
Get through the warranty period and look at a Banks kit.
__________________
Mahof55 is offline   Reply With Quote
Old 08-18-2009, 08:24 AM   #12
Moderator Emeritus
 
Cruzer's Avatar


 
Join Date: Oct 2002
Location: Sheboygan, WI
Posts: 4,902
A 37QDB Allegro Bay is at the heavier end of the FRED chassis applications. You won't be getting the same fuel economy as an Allegro 34TGA for instance. But, there are a ton of factors that come into play also. For one, the unit is new. It takes time for any diesel engine to break in before it will get to it's normal fuel economy numbers. My ISL gradually improved up to 30,000 miles but it tapered off quite a bit at 15,000 miles. Also, you checked it climbing the Rocky Mountains pulling a fairly heavy toad. We do this all the time and it makes a big difference. Your coach probably spent as much time climbing vertically as you did going forward . Of course speed is always the biggest killer of fuel economy. Every 10 MPH that you gain probably costs 1 MPG because the wind drag increases exponentially as the speed increases and it take more horsepower just to move that big brick down the road. I'd give it a bit, then try it on level roads after a few more miles and see what you get. It will improve but I doubt that you will ever see the 11+ MPG that some of the lighter FREDs see.

As to fuel additives I find that I gain very little with them. Fuel additives serve to augment deficiencies in the fuel. If your fuel is decent in the first place you should (in theory at least) not need anything. If your fuel is lacking, old (stale), or you have some adverse conditions (high fuel tank condensation, extreme cold temps, etc) you may find value in them. I've used them in the past but not found any benefit to them in my case. In fact, I've now stopped using them upon the advice of AquaHot. I did have issues with my HydroHot hydronic heating system burner and AquaHot advised me that fuel additives can mess up the burner and take out the nozzle. Naturally, this isn't an issue on an Allegro Bay but I do have to wonder if any of these addditives might affect the emmissions gear, such as the DPF (Diesel Particulate Filter) in a negative way.
__________________
Mark & Leann Quasius
2016 Cornerstone 45A
2007 Allegro Bus 42QRP (Sold)
2012 Jeep Wrangler Unlimited - Rubicon
Cruzer is offline   Reply With Quote
Old 08-18-2009, 10:50 AM   #13
Member
 
ljr869's Avatar
 
Fleetwood Owners Club
Join Date: Oct 2008
Posts: 66
Get your fuel at truck stops, not the normal stations that happen to sell diesel (it sits too long). Keep your filters clean. And another vote for Stanadyne. (I have a F-350)
__________________
Jim
2009 Fleetwood Bounder 35H
Ford V-10 w/ Banks
ljr869 is offline   Reply With Quote
Old 08-18-2009, 03:48 PM   #14
Senior Member
 
Triker56's Avatar
 
Fleetwood Owners Club
Join Date: Jun 2009
Posts: 3,950
Slowing down will gain you MPG.
34' ISB 5.9L 55-58 MPH towing a HHR this summer so far average is 10.991 MPG

I use Summer Opti-Lube http://opti-lube.com/
__________________

__________________
99 Discovery 34Q ISB
2014 MKS AWD EcoBoost Toad
Fulltime Since "99"
Triker56 is offline   Reply With Quote
Reply



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
The Off-Topic Thread MonacoMama Excel Owner's Forum 3405 04-26-2017 12:11 PM
Synthetic lubricants-Aren't??? RV Roadie iRV2.com General Discussion 44 10-15-2014 07:25 PM
Lucas Fuel Treatment Digital Boy Cummins Engines 21 06-29-2009 07:55 AM
Gas Additives - RxP Jeff_E Gear and Product Discussions 2 07-14-2008 02:17 AM
Diesel Lubricity Additive Info EngineerMike Alpine Coach Owner's Forum 17 12-10-2007 08:47 AM

» Virginia Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 01:18 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.