Def for Prevost buses

[sheridany]

I exchanged emails with my Prevost service advisor about the def issue going around that is affecting many brands of class A diesel. They are recommending that we buy jug DEF instead of at the pump.

Keeping it full is a good idea, however we are starting to recommend not using the pumps. We have been seeing coaches come in with codes for poor DEF quality and it was right after they filled up at a pump. We are recommending to use the jugs even though it is a hassle.

 

[Neal]

My $.02 - if you continue to top off, what is the net AGE of your DEF after 10 years, as an example?

This is why on my trip to CO I tried to let it get down to 1/4, I ended up topping off (at the pump) at 3/8. Moral is I want the old out and replaced with new. If you continue mixing old with a little new, what do you end up with?

 

[Rich W.]

That’s consistent with my findings - pump DEF has too many avenues for contamination and you have no control over the age etc. But thats for my fragile Freightlienr system. My Ford seems to be able to digest anything. Also Im told that Volvo has a different emissions system design that is much less susceptible to DEF issues. But still, its easy enough to use box DEF and that is the most controllable method available.

 

[sheridany]

I am not averse to letting it run down as my bus seems to burn def really slowly or the tank is a lot bigger than I am used to. However I’ll heed by their advice to buy jugs to fill it despite the hassle as I want to avoid a derate. Obviously checking the date codes on the jugs is essential.

 

[Neal]

I just want people to be aware that there's more to the DEF fluid quality than the source (pump vs. jug) and we don't know the stories of those coming in for problems as there are a lot more factors to the equation. I think when going in for annual chassis maintenance they should purge the DEF tank and fill fresh and that would solve a lot of the problems if DEF quality is a contributing factor. They change out oil, why not DEF?

Edit: I'm going for my annual FL service at the end of this trip and I will be inquiring about care of the DEF system? I don't know what's been done in the past, if anything and it's probably time for me as the owner and them as the service center to be more proactive in mitigating the DEF problems we now have a history of to learn from.

 

[sheridany]

Prevost has a DEF service which includes draining the tank and installing a new filter. I will do that when I go in November for my annual.

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