DEF diesel engines

Diesel exhaust fluid, is an additive on newer engines to enable it to meet the new EPA standards, or IOWs to enable the Greenies to grab more of your money. the older non DEF run great with out it on ultra low sulphur fuel.

DEF is introduced in the exhaust stream and has no effect on engine power.

JumboJet wrote:
DEF is introduced in the exhaust stream and has no effect on engine power.

While the statement is true, it may be a little misleading.

Because of DEF, the engines can be tuned for more power and better economy.

Very similar to what happened to gasoline vehicles between 1974 and 1975 when catalyst converters were added.

Don't know about DEF, but the rule of thumb for engine size vs RV weight is a minimum of 1 HP/100 lbs. HP = GVWR/100. So if you have a 33,000 lb RV, the LEAST you'd want in engine size is 330 HP. Seems to me of the rigs I've driven, that rule of thumb is fairly accurate.

wolfe10 wrote:

JumboJet wrote:
DEF is introduced in the exhaust stream and has no effect on engine power.

While the statement is true, it may be a little misleading.

Because of DEF, the engines can be tuned for more power and better economy.

Very similar to what happened to gasoline vehicles between 1974 and 1975 when catalyst converters were added.

I was referring to the post title "DEF diesel engine". The engines are designed for leaner burn but produce a nasty exhaust that the fluid converts to water and nitrogen via the SCR.

Are the newer engines that require DEF actually providing better economy or just tuned for more HP?

What year did they switch to DEF ?

No disadvantages of going with an older non DEF diesel. Only disadvantages with a newer DEF diesel is the after treatment system made engines more expensive and that cost is likely rolled into whatever chassis/coach you are looking at.

kgard1225 wrote:
What year did they switch to DEF ?

2007, but because those engines ALSO required Ultra Low Sulphur Diesel fuel, which was not available, there are almost no 2007 diesels on the roads. Such as there are were probably imported by an individual.

Engines that require DEF will be newer and this most likely have fewer miles on them. Adding DEF is neither difficult, nor onerous, nor for that matter expensive. It is made of two of the cheapest industrial chemicals known to mankind, so whatever you pay for it, the cost is nearly all profit for somebody.

All the engines that use it also have a warning the computer pops up to alert you to refill. On my SUV, the warning is "DEF required, 999 miles until engine will not start." Since DEF is available all over the place, there is no place you can possibly go such that you can't get some DEF within 999 miles.

The prices I've seen range from a little over a dollar a gallon to $17 a gallon, and since the DEF recipe is defined in law, one brand is exactly the same as any other, so buy the cheapest you can find. Adding it is simple. If you can physically put gas/diesel in the fuel tank, you can add DEF.

As others noted, it allows engines to be tuned to deliver more power at greater economy while cleaning up the air we all breathe. Who can oppose that?

My SUV, again for example, has a 6 gallon DEF tank, and that is supposed to carry you 12,000-15,000 miles. Last jug of it I bought cost me $6.95 for 2.5 gallons. At that rate, it's about 1/10th cent per mile. You be the judge whether you can afford that.

kgard1225 wrote:
What year did they switch to DEF ?

the clean burn diesels came out on 2007 through 2009 approximately and then the DEF engines where u actually add fluids started around in the 2010 area
I think the systems where u add the fluid is better than the 2007-2009 clean burn ones.They had the DPF systems and when they go bad its expensive. Mufflers are like 3800$

Avoid 2008+ diesels which do not used DEF. These will use heavy EGR instead to meet emissions. These are the problem motors. Any of the DEF-euqipped diesels are fine, as are any diesels pre-2008 (beware that some late 2007 diesels may have 2008 emissions... avoid those too).