tlbray Report post Posted April 12, 2016 I recently spoke to a motorhome salesman and he said newer diesel motorhomes required an additional fuel tank that would contain a diesel fuel additive that cost $5 per gallon and would hold up to 17 gallons. The exhaust from a diesel would then mix with this additive before being released into the atmosphere. The additive would last about 3 tankful's of regular diesel fuel before having to be refilled. Do older diesel motorhomes have to be retrofitted to meet the new regulations? I'm confused. Share this post Link to post Share on other sites
manholt Report post Posted April 13, 2016 Time to talk to another salesman! All diesel engines from 2010 to present have a DEF system, most DP RV's have a 11 or 13 gallon DEF tank and it's set up to deliver a pre set amount. I had it on a 2011 Allegro Bus and it held about 9 gal. of which I would use about 6 gal. of DEF for about 4,000 miles of travel (150 gal. fuel tank). DEF cost about $3,50 gal. You don't want to run lower than a 1/4 of tank. Due to the way my DEF tank was constructed, I only got 9 in an 13 gal. tank. Share this post Link to post Share on other sites
wildebill308 Report post Posted April 13, 2016 Carl is a faster typer than I am. This is my input. I would not be scared of a coach using DEF. It has been required since 2010. The big benefit is coaches running DEF get better mileage and have more power. Here is a article about it: http://www.truckinginfo.com/article/story/2013/06/def-here-to-stay.aspx I don’t have to use it but friends have reported roughly 50-1 ratio. One gallon DEF to 50 gal of diesel. As they say your results may vary. As to cost I just checked on my Pilot/ Flying J app and DEF at the pump is $2.799. No older coaches do not have to be retrofitted. If I was looking at a 2009 and a 2010 and they were close in price I would get the 2010 because I think they run better. (All things are subjective). Bill Share this post Link to post Share on other sites
wolfe10 Report post Posted April 13, 2016 tlbray, Welcome to the FMCA Forum. You have received some bad information. Yes, many late model diesels require DEF (Diesel Exhaust Fluid). Current prices of DEF are under $3/gallon: http://www.pilotflyingj.com/fuel-prices As far as DEF consumption vs fuel consumption: https://www.cumminsfiltration.com/pdfs/product_lit/.../MB10033.pdf On page 6: Q. How can an operator determine how much DEF they will need/use? A. DEF consumption will be approximately 2% of the diesel fuel consumed. Another way to consider it is that DEF will be consumed on a 50 to 1 ratio with diesel. (For every 50 gallons of diesel fuel burned, you will use 1 gallon of DEF). If you know the average fuel consumption of a vehicle, you can easily calculate the amount of DEF that will be used. Not suggesting you want a coach with this system, but DO want you to have the FACTS! Share this post Link to post Share on other sites
dickandlois Report post Posted April 13, 2016 tlbray, Welcome to the FMCA Forum! The Environmental Protection Agency - EPA has mandated a number of changes to improve emissions. The first major change came in 2007 with more requirements coming in 2010. The requirement for Diesels to use Diesel Emission Fluid came out in 2010. This is the new requirement the salesman was referring to. The older engines before 2007 do not need to be up graded to the 07 regulations or the 2010 regulations and the same is true for engines built from 2007 to be upgraded to the 2010 regulations. Rich. Share this post Link to post Share on other sites
jleamont Report post Posted April 13, 2016 A few things to add: Diesel Exhaust Fluid goes into the DEF tank only if equipped. If not equipped you do not need it at all. Countless times I have read where people in coaches were trying to be more "green" and were adding DEF to their Diesel FUEL tanks, this mistake will cost you thousands $$. If you do purchase a Diesel Motorhome requiring DEF make sure you do not mistake the tank for the washer fluid reservoir. They both have BLUE caps, normally the windshield washer reservoir is in the front and DEF tank is on the side closer to the engine if its a Diesel Pusher (toward the rear)......it happens. I recommend reading the manual and familiarizing yourself with your coach, I do NOT recommend asking the sales person to explain it and where to add it. We had a driver fill a DEF tank at work with Diesel fuel, that didn't go well either. Share this post Link to post Share on other sites
dorgene Report post Posted April 13, 2016 Keep in mind that the diesel engine emission regulations apply to the model year of the ENGINE, not the chassis, not the coach. For instance, you could have a 2009 engine in a 2010 chassis in a 2011 coach and it will not require DEF. DPF's (Diesel Particulate Filters) were required on 2007 model year engines and SCR (Selective Catalytic Reduction) using DEF (Diesel Exhaust Fluid) was required on 2010 model year ENGINES (except for some Navistar/Maxxforce engines). Share this post Link to post Share on other sites
manholt Report post Posted April 13, 2016 Mine is a 09' engine on a 09' chassis, December. Coach was built in January 2010. Close call. I use DPF. I have had a DP that required DEF....got .06 more mpg than current coach! It was an 11' coach with a 450 Cummins 37' ! Share this post Link to post Share on other sites
five Report post Posted April 14, 2016 Wally World has come out with their own brand of DEF...I think it's less than $8 for 2 1/2 gallons. Share this post Link to post Share on other sites
manholt Report post Posted April 14, 2016 Flying J=2.799 x 2.5=6.999... Share this post Link to post Share on other sites
