New to owning a diesel

[bigb56]

Originally Posted by tuffr2

I have read DEF has no preservatives so the self life is about a year. I also read it will crystalize. I am going to my local Walmart in the next few days. I will look on the box to see it there is a manufactured date. I used DEF for 6.5 years but never looked at the box that close. Also I knew the DEF would not be in the truck that long.

Ever wonder what percent of DEF is bad in the DEF reservoir ? I do, but not often. Same for diesel and same same for gasoline. Seems to me that you are always mixing new with old. Some of that old stays in the tank. Eventually some of it will be bad but you keep mixing in new.

I had a case where 1/2 of my DEF was 9 months old. Then I added 1/2 new DEF. That took 4 months to use. So 1/4 of my DEF was over 1 year old. I never had a problem.

DEF can last much longer depending on how it is stored. When you add fresh I don't think you need to worry about the old that was in there, the fresh will mix in and I think you're OK.
Some manufacturers use regular dates but if looking at the boxes of Blue DEF you will need to research how to read "Reverse Julian Dating" which is what they use to keep us in the dark.

[NLOVNIT]

LAST WARNING!!!

Several posts have been removed for continued arguing as well as disregarding Dan's thread warning earlier. Both Community Rules violations.

If you can't keep it on topic, don't post or this thread will get closed quick.

[Super Thirty]

I have been running a diesel that requires DEF for about 7 years now. From my perspective other than adding DEF periodically the maintenance hasn’t changed from pre DEF units. If you live in a cold climate like I do be prepared for DEF issues from freezing. I have experienced issues with DEF freezing with both trucks I’ve had. IMHO it is a poorly designed system for operating in temperatures below -12C. The manufacturers know this is a problem and have done nothing that I’m aware of to improve it. My truck sat for over 6 weeks because the DEF system froze and they couldn’t supply the parts needed. There is no way to legally bypass the system when it’s frozen so I had an expensive driveway ornament. Hopefully enough owners have problems and get mad enough to file a class action suit against the manufacturers.

[tuffr2]

Here is a picture of the box. On it you can see what looks like it could be a Julian date.

Can anyone decipher this date code?

[bigb56]

It's Reverse Julian dating. The GB is the manufacturing plant, the 23 is the year minus one so 2022, the 306 you subtract from 365 to get 59 so it was manufactured on the 59th day of 2022. I usually buy at Costco where it is seldom more than 2-4 weeks old, I wouldn't buy that one unless you use a lot, it's almost 9 months old. My Sprinter only uses about 6-8 gallons a year and my TDI less than half that much, so I want it fresh.

[tuffr2]

Wow - already 9 months old. I used to buy all my DEF from Walmart and never looked at this box. This box was over $16. The last time I bought DEF was in early 2018 and I think it was around $7 then.

People that drive a diesel U.S. Jetta for example probably do not use very much DEF. They are probably more at risk having bad DEF issues.

[bigb56]

Originally Posted by tuffr2

Wow - already 9 months old. I used to buy all my DEF from Walmart and never looked at this box. This box was over $16. The last time I bought DEF was in early 2018 and I think it was around $7 then.

People that drive a diesel U.S. Jetta for example probably do not use very much DEF. They are probably more at risk having bad DEF issues.

Yeah my TDI Sportwagen holds 3.5 gallons and uses about a gallon every 3,000 miles.

If you live in a cooler climate and can use up that DEF within the next year or so I would run it. DEF that doesn't see a lot of heat can keep longer, over 3 years in some cases. I have to be careful here in the desert though.