advice for a 2015 lone star

Try to FASS fuel system. Extra fuel filters will make fuel more cleaner. A dirt that is much as gun powder in a bullet shell will kill the common rail fuel system engine.

 

my friend has the same year, it's prostar, 10 sp ultashift, 450 hp, super singles, and gets 9 mpg.

 

trukngrl what are you getting mpg out of your truck now? What do you get with lighter loads?

 

Saw that someone recommended synthetic 5w40. Not a bad suggestion, but I would go with a synthetic 5w30 or 10w30. Reason? All new heavy diesel motors are factory filled with 10w30. 40w oils are old school now. There are some pretty good 10w30 synthetic blends available. Mobil has one that is a very strong product. I like Schaeffer oil, and they are supplying some fleets with newer motors a solid performing 10w30. One of them, if I recall clearly, is Trans Am out of Olathe, KS. I know the Canadian outfit Trans West is on 10w30 for their normal oil now, I think they are on Delo. Lots of other fleets already using it also. A guy I know at my carrier bought a new 2015 Prostar he ordered with a 500 ISX, and it was factory filled with 10w30, and he has run 10w30 in it since the first oil change. Doing great. He popped a 9 mpg average last week for the week.

Don't let the number in front of the "w" fool you. A 5w40 or a 15w40 are both 40w oils. The number in front of the "w" is the "winter flow rating". A 5w40 just flows easier when cold than a 15w40. But at operating temperature, they are both the same 40w oil. A 5w30 or 10w30, each are 30w oils. If one is looking to oil for some efficiency improvement, going to a 30w oil is going to net better results. Synthetic, just that much better.

I like the Scangauge too, and have used them on my last two trucks. But forget the KR version and its inflated price. You can get a Scangauge D that does virtually everything the KR version does but cost's about $70 less than the KR version. You can get one on Amazon or from Scangauge themselves. Pay $228 if you want for the KR one or pay $159 and free shipping for one off of Amazon.