Recently I've noticed the on pump warning... (this)Low ash fuel should not be used on 2007 or newer engines. Also mentions using this fuel may ruin engine????? Is this true? why? and where do I buy diesel fuel then?

Diesel engines manufactured after 1-1-07 are equipped with diesel particulate filters which trap diesel particulates in the exhaust.

They are designed to run Ultra Low Sulfer Diesel (ULSD) which has 15ppm Sulfer. Low Sulfer Diesel (LSD) has 500 ppm sulfer, and can damage the dpf's.

I am not familiar with the equipment on GM diesel engines. I would advise you to call the GM tech line to ask the question regarding your specific engine.

Thanks for the reply Pusherman. Explained that way I realize my 07, manufactured in 06, dosen't have the same system. The way I understand it, the ULSD engines burn off excess diesel fuel in the exhaust system(huge exhaust pipes) rather than pump it into the atmosphere. I was worried I was harming my engine but not so. Thanks.

quote:

Originally posted by brad03ca:
The way I understand it, the ULSD engines burn off excess diesel fuel in the exhaust system(huge exhaust pipes) rather than pump it into the atmosphere. I was worried I was harming my engine but not so. Thanks.

There is no such thing as excess diesel fuel. The ECM precisely calculates the amount of fuel needed and it is injected into engine cylinder and burned.

The new diesel particulate filter may from time to time need some added heat to regenerate the filter and this is done by adding minute droplets of fuel in the exhaust stream of the turbo. These minute droplets burn in filter and never see the exhaust stream post filter.

ULSD will not harm the engine, rather it will ruin the particulate filter with continued use. In an emergency you can get by with using a few gallons of LSD fuel without permanently ruining the DPF, but it may shorten it's useful life.
For more information about USLD and diesel engines, visit: Exxon.com and drill down to the diesel fuel FAQ page. Better yet, run an internet search for ULSD.

Just to add some clarification to this thread, the latest version of the Duramax (LMM) uses an exhaust filter that traps particulate matter, or soot, which is generated during the diesel combustion process.

When the ECM calculates that the percentage of soot has reached a certain level, the system begins a regeneration process to incinerate the soot that is in the filter. This is done by altering the amount of fuel injected into the cylinders, changing the incoming air rate and closing the turbo vanes among other things to dramatically increase the exhaust temperature. Once regeneration is complete, the ECM begins to monitor the "Soot Model" again until another regeneration is needed. Eventually, the filter will become full of incinerated soot and need to be replaced.

Now, in order to prevent permanent damage to the exhaust filter, these engines should be run on ULSD fuel (15 ppm or less) and use low ash, CJ-4, engine oil.

So, Brad, it sounds like you have a GMC Sierra "Classic" with the LBZ engine that doesn't require the special fuel and oil.

Correct goodwrench and Thanks. Being a new diesel owner, I saw these pump warnings and panicked. Now I know things are OK I can relax.

Is it just me...or are these trucks super fast. They sound like a truck but go like a race car..... Yeha!

I should have added a link to the website explaining this entire subject and the 1-1-07 date. The exact regulation clearly states "all 2007 model year engines". It is perfectly fine to burn S15(ULSD) fuel in a carry-over 2006 engine in a 2007 vehicle(existing stock only).