naturist
Veteran Member
- Joined
- Apr 2, 2001
- Location
- Bro Jerry's hometown, Virginia
- TDI
- 2001 Jetta TDI, 2005 Jeep Libby CRD, 2012 BMW X5 35d
Sorry, nonsense. The composition of DEF is specified in the EPA regs. They are required to make it to spec, and they can't add any "special sauce," not even dye, to distinguish theirs from all the others. It is ONLY urea and distilled water, at a fixed ratio, and there are no variations allowed. The result is that DEF is a commodity, one brand is the same as any other. There is NO difference in quality. Buy the cheapest one you can find; you are getting exactly the same stuff as the most expensive brand you can find.There's a lot of difference in the quaility of the DEF fluid out on the market but as long as you're buying a good quaility ISO certified DEF in a sealed container you should be fine. Contamination is the biggest issue with DEF. VW can only deny warranty strictly related to the part failed so if like your HHFP went out they can't use DEF as an excuse to deny warranty of a totally un-related part.
As for DEF vs. HPFP, at no point does the DEF come in contact with the HPFP, so there is never any reason why the one should have any bearing whatsoever on the other.
The only issues with DEF is (a) whether you are actually buying DEF, as some folks have been known to buy a jug, pour it into their truck, refill with tap water, and return the jug to the store for credit; and (b) when pouring it into the tank, some idiot has managed to add grease, oil, or plain water in the process. Some folks can't take a whiz without hosing down the entire room, you know what I mean?