my duramax is an lb7 series, and if you do some reasearch on them you will see injector failure is there biggest issue. and from what some old timers have told me it is largely low sulfur fuel. my truck is smoking quite a bit lately, it will soon be going to a dealer for them to test the injectors. a set of them is about $1800 plus the days to put them in. so anything that might prolong there life is worth looking into.....save the should have bought a dodge comments please......