DEF

[Cobblecrazy]

I had to make a Costco run today, and while strolling through the isles I came across a display of 2.5 gallon jugs of Peak Blue DEF. I noticed the price was just under $10. About a week ago I paid in the neighborhood of $30 for almost the same jug of Mopar DEF. While I knew there were different price points I had not gone over to the auto parts store to do any price comparisons.

The DEF system is new to me; however, I have done some reading to better understand what the fluid is, and what it does.

When I was having the initial issues with my Gladiator, I spoke to the service guy at Jeep about the DEF as it seemed to be going through the fluid a little faster than I thought it should. Throughout our discussion he kept reiterating how it was important to stay with the Mopar brand. I know most things are just marketing and I am always leery of these types of statements. I asked about alternatives if I found myself in a location where Mopar was not available. He mentioned a few brands (Peak Blue included), but I got the impression if there was an issue related to the DEF you’d have an easier time if you had been using their brand. I have read the manual where it gives some DEF standards so I want to compare the info on the Mopar jug and the others (beyond just the API certiication).

As with most discussions I’ve found the gambit of “well I’ve used this or that and my engine‘s run for a billion miles so it’s fine“ to “bought some cheep stuff and engine blew up a mile down the road”…. What I’m most interested in hearing is issues with the DEF system using off brands and how mother Jeep has responded, what (if any) differences in performance/longevity have people seen using “other” brands, and if anyone has really looked into where Mopar gets their DEF and how/if it is really different from the top brands out there.

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[WXman]

DEF brands are like bottled water brands. There are dozens of different ones, but they're all the same thing.

I get mine at Walmart. $7 for a 2.5 gallon jug. API certification on the jug. No issues.

Keep in mind that DEF usage decreases with time.

 

[2TH MVR]

Need to check the expiration dates. Right?

 

[maxpower220]

I have found that DEF is cheaper if you buy it at the pump at the filling station. Almost all "truck stop" stations have it and it is becoming more popular at large car filling stations. Like gas and diesel, a high turnover station will have fresh fuel and DEF. It is also easier just to use the pump and not handle a 2.5 gallon container.
YMMV depending on where you live.

 

[HighNoon]

There is also storage temps range on the def. I don’t quite understand the reason for storage temps because in real world use it’s out of the range quite often once in the tank.

 

[WXman]

I have found that DEF is cheaper if you buy it at the pump at the filling station. Almost all "truck stop" stations have it and it is becoming more popular at large car filling stations. Like gas and diesel, a high turnover station will have fresh fuel and DEF. It is also easier just to use the pump and not handle a 2.5 gallon container.
YMMV depending on where you live.

There is also storage temps range on the def. I don’t quite understand the reason for storage temps because in real world use it’s out of the range quite often once in the tank.

And that's sort of a reason I prefer the jugs. They're stored indoors, they're marked and labeled, they're date coded, you know exactly what you're getting. From the pump, you have no idea what's actually in that tank. I don't believe DEF at the pump is regulated like diesel fuel is.

 

[Free2roam]

@Cobblecrazy here in town. A place I used to work at, they make it there. Re-bottle all sorts of brands of DEF.Same goes for windshield washer fluid. Highline aftermarket over off Greg.

 

[shyoung1]

DEF is DEF, and you don’t use much of it anyway.
At least my 6.7 Superduty doesn’t.

 

[Hootbro]

There is also storage temps range on the def. I don’t quite understand the reason for storage temps because in real world use it’s out of the range quite often once in the tank.

The reason for the recommended storage temps and also to have the freshest date DEF possible, is to give it that extra margins of having decent useable life once it actually goes into use and is sitting in the vehicles DEF tank.

General rule of thumb when I ran a diesel vehicle with DEF, was to never have the DEF fluid either used to refill or sitting in the DEF tank go no more than 8 months to a year before putting in fresh DEF.

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