1994 7.3 non psd turbo 179k miles.
2005 Duramax 60k miles.

I want to know the difference between a cai and a dia. I was told by a GM mechanic that a cia is not good for the MAF. He says the oil will coat over it and can cause mpg problems. I am hoping to figure out a way to increase the mileage on the duramax. I am only getting 13.8 mpg. I was expecting better then that. Well, I know just enough to be dangerous, cai, exhaust and chip. But for thousands of dollars is it really worth it to beef these trucks up? I have also made bio-diesel. I run it in my kubota diesel riding lawnmower. It is pretty cool actually. But I have not mustered up enough courage to run it in either of my trucks. Anyway, long post sorry, just looking for comments and ideas regarding these 2 trucks. I drive the duramax every day, it is my work truck.

Looking forward to reading the commnets.

CAI, is cold air intake. which usually is a replacement air box, filter and intake tube. They give you a little better throttle response, little more power. The most common does have oil on it. Where folks have problems is when cleaning they add too much oil. The new trend is toward dry filters in the CAI. More at http://mrtruck.net/afe.htm The new trucks owners manuals say 5% bio diesel. When I've tried it, no change in the Duramax, little better in the Power Stroke. I know of some dragster diesels that use 100% bio diesel. It's a better deal than methynol in gas. You'll see more of used in the future.