In my '95 F-350 4x4 7.3 DI, I usually saw about 16 in town, and about 20 on the highway. (5-60). I started running Marvel Mystery Oil in my fuel, and it netted me appx. 4 mpg. I not routinely see 20-22 in town, and 25+ on the highway. (though I keep my foot out of the turbo and the injectors). I also tend to keep my speed to 55 mph. (I have an '05 VW GTI to go fast in)
Most people find my mileage to be rather unbelieveable. So here are my numbers. To 3/4 of a 15 gal tank (10.75 gal) used, I usually get anywhere from 220-240 miles. I do check my "exact" numbers when I fill up at the pump, but these are my average numbers. This week, my front tank got me 230 miles. Just switched to rear, and I've already put 93 miles on and I'm not down 1/4 tank yet on the rear.
It's all in the fuel. USLD sucks dirty a**. The sulfur is removed, and in turn, so is the lubrication provided by the fuel. Simple....add something to increase the lubrication of the fuel. I use Marvel, but there are lots of products available. (I've got a friend w/ a cummins, and he adds 2 cycle premix oil to his fuel)
I might have to try the 2 stroke additive. I don't want the Marvel going through my injectors. It might not hurt. But, man that stuff looks gunky in the bottle. I've been averaging 17 mixed driving for awhile now. It is hard to keep the foot out though. I have to set the cruise and find something good on the radio or I'm back at 80 and sucking fuel like crazy.
Well, to each their own. Marvel is fairly thin, like a 5W oil. But offers lubrication, cleaning, and so on. All I can say is what I get. Your rig might be different. (who knows) I don't know if my buddy gets any added fuel effeciency using the 2 cycle oil or not. He uses it more to keep his (older style) fuel pump on the tollerably loud side. (I don't know much about the different fuel pums that Cummins uses or has used, so I can't say any more) But, I'd imagine that adding an oil to the fuel, couldn't hurt, that's for sure. (especially with the lubrication side, as that's why it's added to 2 stroke fuel)
You'll have to let us know how it goes for you, and if you pick up any added mpg.
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