ULSD vs. LSD when it comes to MPG - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• ULSD vs. LSD when it comes to MPG by 89VWdieselGolf on 12 Feb, 2008 12:58
• I know our motors were designed when LSD was in effect. And i've heard that ULSD isnt good for them (although im not sure why.. something about the IP leaking :? )
  
  Because of them not being used to the ULSD, would get get better mileage using LSD or using ULSD?
  
  thanks,
  Jeff
• #1 by coke on 12 Feb, 2008 13:01
• There is a lot of speculation on ULSD. One thing we can be sure of is it has caused a lot of leaks in older pumps.
  
  I also believe there is some good evidence that determined ULSD doesn't generate as much internal pump pressure in the injection pump which causes the advance mechanism in the pump to not advance like it should. This causes a retarded condition in respects to the dynamic timing advance.
  
  I increased my internal pressure and it made a huge difference. Especially on fuel mileage.
• #2 by 89VWdieselGolf on 12 Feb, 2008 13:42
• ya i want to do that increase internal fuel pressure mod, but im not exactly sure how. I'll try the LSD.... I've been getting 667.1kms(weird.. two times in a row) to the tank with sunoco, which is ULSD. I've replaced the fuel filter, and a sketchy return line and now i'll try out some LSD and see what happens.
  
  Does anyone know if shell's diesel is LSD or ULSD? I know petrocanada's is LSD (says on the pump)
  
  thanks again,
  Jeff
• #3 by 89VWdieselGolf on 12 Feb, 2008 14:00
• did some research on shell's website, and it looks like they may use ULSD (as well as going on about how the V10 TDI uses their fuel)
  
  but it doesnt say anything about their regular diesel, just the ultra and v-power diesel (although i've never seen v-power diesel, just 91 octane gas which i use in my gasser)
• #4 by clbanman on 13 Feb, 2008 06:47
• Quote from: "89VWdieselGolf"

  I know our motors were designed when LSD was in effect. And i've heard that ULSD isnt good for them (although im not sure why.. something about the IP leaking :? )
  
  Because of them not being used to the ULSD, would get get better mileage using LSD or using ULSD?
  
  thanks,
  Jeff

  
  
  According to a service bulletin we sent out to our customers, ULSD is not only changed by the reduction of sulfur content, but by "eliminating fractions in the oil having a heavy molecular structure". This results in a "lower specific energy content than standard diesel fuel, in some cases by as much as 15%".  Based on that information, I would expect a mileage decrease.