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Everyone is asking us about Pig Urine…

Our web gurus track the number of people that read my articles and they always tell me an intriguing title will catch the reader’s eye. I’m going to bet that this week’s title breaks the record for grabbing attention. I’ll let you know the results next week.

Pig Urine really is the talk of the RV town lately. Let me explain.

Most new Motorhome diesel engines now have a special tank that holds Diesel Exhaust Fluid (or DEF). This fluid is composed of Urea and deionized water. Pig urine (or cow, horse, even human) is largely urea and many people refer to DEF as pig urine even though the majority of DEF on the market is not made using animal byproducts. Regardless, the name has stuck.

The addition of the DEF tank to your motorhome engine enables the exhaust to be “scrubbed” with a mixture of DEF and air and the resultant emission is converted from noxious fumes to harmless nitrogen and water. Sounds like a good idea, huh?

It is -but there are concerns…

DEF adds another step to your maintenance process. And it’s an important one. You really don’t want your DEF tank to run dry on a long trip. Resultant repairs are in the $12,000 range. Many of today’s new motorhomes have an added dash gauge, similar to the fuel gauge but some owners don’t like the thought of another thing to keep an eye on. The good news is your motorhome sips DEF (unlike diesel) and a full tank should last thousands of miles. However, if you run low your engine might automatically shut down or refuse to turn over in a self-preservation move. Don’t forget to pack a fresh bottle of DEF for the trip.

Fresh bottle? Yep. There is a shelf life to DEF and each container shows an expiration date. This makes it difficult to just toss a bottle in the storage compartment and forget it. You have to keep an eye on the date and replace it when necessary. Again, not a huge deal but definitely another important step.

DEF FillSome tanks fill at the pump island at truck stops now, just like fuel. Convenient, yes, but don’t top off both tanks while distracted. Mistakenly introducing DEF directly to your fuel tank produces a concrete-like mixture inside your engine and I think that would adversely affect your performance. Apparently enough owners have done it, though, that many Motorhome manufacturers now make a point of placing the fuel and DEF fill points at opposite ends (and even opposite sides) of the vehicle to avoid confusion. It works but now you may have to fill your fuel tank, move the vehicle to the other side of the fuel pumps, and then top off your DEF. Inconvenient, yes, and trying it with a 35’ Motorhome at a busy truck stop probably won’t be fun –or earn you any new friends from those waiting behind you. You can carry a few gallons with you for situations like this but, again, another step.

DEF also freezes and when it’s frozen it obviously can’t be introduced to the exhaust. The freeze point for most commercially available DEF is listed as 11 degrees. Cold, yes, but not THAT cold. If you’re heading south from Minneapolis for a long vacation in the sun, and your Motorhome has been parked for an extended period of time prior to leaving, and it’s January, there’s a good chance your DEF tank is frozen solid. The good news is that your Selective Catalytic Reduction (SCR) system is designed in a way to heat the tank and lines to full thaw prior to engaging the transmission. The SCR will enable you to start your engine with a frozen DEF but you may be waiting an extended period of time for it to fully thaw. Dealing with it once before heading to Florida probably won’t be a problem, but for those four-season travelers who like to head north (Canada, for example) it could be a frequent annoyance.

There are other concerns. Many owners claim the introduction of a new, complicated and critical system to the simplicity of the diesel engine makes the added expense of a diesel less appealing versus a traditional gas engine. Some claim the DEF systems adversely affect fuel efficiency, power, and maintenance costs while others insist DEF improves these items.

Here at most people tell us the driving experience between a pre-DEF and a DEF Motorhome is unnoticeable and that the maintenance and monitoring of the system, while an added burden, soon becomes just another part of owning a Motorhome.

How about you? Do you have a DEF story or opinion of your own? Drop me a note at [email protected] and fill me in. Interesting or informative comments will be shared with the group next week. If you want to share with me the story of the guy who peed in his DEF tank in the desperate hope that it would get him to the next filling station, please don’t. I’ve already heard it about five times and, no, it didn’t work out very well for him, from what I heard. Stories about traveling with your own pig are strongly encouraged, however.