Yeah, D2 really doesn't thin nearly as well as K1. I knew that already, but I've really "learned" it this year. I run 3 or 4 tanks of straight D2 when I switch over from WVO to WMO. In the past I hadn't really looked into WMO much because of the additional smoke, and the added wear on the engine. I figure since the engine is old already, I should be nice to it
My main focus is cost of operation as well. I started down the road of Bio, but the more folks I spoke with, the less that made sense. Then I moved to WVO and only realy looked at WMO for use in the winter when I can't use WVO reliably. I have to pay for decent WVO, but it's still cheap compaired to D2, even if I cut it with K1. I've only reciently stumbled across the idea of using WI to keep the engine clean, and the more I read up on it the more I like it. Based off of my very limited readings so far, it appears that there are guys who are running late model trucks on high percentage WMO blends with single tank systems. That opens up a whole new door for me as I've been trying to figure out what our next vehicles will be for the last couple of years. The wife drives 45 miles each way to work (loves her job though, and it's only 3 days a week for excelent pay). She's in a 2004 CRV right now at 25 mpg. The idea of water injection could open up the possibility of an '03 Excursion. Not sure what part of IN you are in, but round here when it does finally snow, the wind will often blow the highways closed. Wife starts her drive home at 2:00 AM, and between the snow and the deer, I like the idea of the Excursion over the CRV. Plus I don't have to bend over to strap the kids into their seats. Also opens up the same doors for the replacement of my truck when it comes time, which is my real concern. We heat with firewood, we eat a LOT of deer meat, and we camp, so I pretty much have to have a truck in the drive way, and having one that's 4wd is a major bonus. With 2 kids, and both of us working, both vehicles have to be able to hold the driver plus 2 car seats, which puts me into an extended cab or crew (with a strong preference to the crew). While I don't need 400hp, I do need something that can handle 5K~6K of wet oak stacked in the bed. Oh, and I beat the heck out of them. I don't want no perdy truck

Since the truck becomes my daily driver by default (50 miles/day round trip), the fuel costs are a noticable factor in the decision as well. By the time it's said and done, we would be looking at $15K~$20K per vehicle which is way out of our budget for something that gets 15~20mpg with fuel that's $3.75 to $4+ a the pump. However, if WI truely opens up the door for using WMO in late model engines, that's a game changer. Our fuel bill last year was around $7K. Running two diesels on WMO would drop that to under $3K. How far under would depend on the blend, but it's possible it could go as low as $2K. Cutting our anual cost of living by $4K to $5K would allow me to open up the purse strings a LOT farther when considering future purchases.
I'd like to keep my truck forever, if for no other reason than I can take it out in the woods and beat the tar out of it and still have a smile on my face. But it would be nice if my backside didn't know where every little bump was on the way too and from work. And the truth is that in another 2 or MAYBE 3 years, the body and suspension on the truck are going to be so far gone that she's no longer suitable for a daily driver. So while I like the fact that I can run just about anything in my truck's stock system (once it warms up), the truth is that I have to watch what I spend on things like a centrifuge, a collection system, and so on because I only have a very finite amount of time to recover those costs. Once again, however, if WI actually makes using WMO a good, long term option on late model diesels, it becomes an entirely new ball game. Still more research to do....