That isn't true. Diesel is batch tested before it ever leaves the refinery.

My $0.02 as a refinery engineer.

The ULSD meets the same lub spec as LSD did.

The difference is that ULSD will be additized to just meet spec. LSD easily exceeded the spec with no additive.

ULSD lubricity should be just fine. LSD lubricity was better than just fine.

__________________
1982 300TD 279K.
1984 190D 5sp 265K

I have to differ with these opinions. "Star Magazine" did an article a few months back (June, I believe) where diesel had been tested in various locations and it did NOT meet the minimum specs for lubricity.
The article is Star magazine, Jul/Aug 2007 'New Diesel Fuel and Old Diesels" by George Murphy pp 84-86

The article had great information about how the junk they are selling as ULSD does not meet the minimum lubrication requirements for even new engines much less our old ones. "Of 27 countries surveyed, only Canada, Switzerland, Poland and Taiwan have worse diesel fuel than the US." There was a grid in the article that showed lubricity levels in various cities. If I remember correctly, only one city came close to the minimum standard. I wish the article was available online so I could link to it, but STAR does not post articles.
According to the article MB likes Lucas fuel treatment and Octal OLI-9070 as lubricity enhancers. They also like B5 BioD but not a higher percentage.

If the stuff coming from the refineries meets the standard, what is happening before it reaches the pump? Can the lubricity agent be precipitating out of the fuel?

Do what you want, but I will stay safe and keep adding Lucas to my tank!

__________________
"I have no convictions ... I blow with the wind, and the prevailing wind happens to be from Vichy"

Current
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Gone
'74 Jeep CJ5
'97 Jeep ZJ Laredo
Rudolf ‘86 300SDL
Bruno '81 300SD
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'92 Subaru
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'71 Buick GS conv
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'57 Nomad

Well I stand corrected. I didn't know it was that bad.

The diesel is not in spec leaving the refinery. The additive is added at the fuel terminals. Terminals generally don't have a full lab and 15 chemical engineers on staff, and I've seen some interesting things happen at terminals that you wouldn't see at refineries just from the lack of technical expertise.

The additive is also very expensive so I can guarantee that only the minimum amount is put in. What was just good enough today may not be good enough tomorrow. I have no idea what kind of testing the terminals do on this.

I saw a presentation from an additive provider a few years ago. He had a chart showing a ppm addition vs. % fuel meeting lub spec. It implied that you chose what percent of your diesel you wanted to be in spec and added x ppm. That's pretty messed up. There are no other fuel specs that are negotiable that I'm aware of.

__________________
1982 300TD 279K.
1984 190D 5sp 265K

Search here and on MBCA and you will find that article was contradictory to a few of the Star's own previous articles.

Diesel is tested before leaving the refinery for:

API gravity
CETANE
Distillation
Copper Strip
Color
CONDUCTIVITY
VISCOSITY @40C
DOCTOR TEST
SULFUR
FLASHPOINT
HAZE
POUR POINT
CLOUD POINT

__________________
1982 300TD 279K.
1984 190D 5sp 265K