OK here's the new versions. I can't attach a Excel spreadsheet so if you want it shoot me a PM and I'll e-mail it to you. The gas version is based on my '03 Silverado Z71 with the 5.3L. The diesel version is based on my '93 Dodge Cummins. If you push your change interval to 15000 then the bottom line on the diesels becomes much better - in my case it's $697.14 savings every year at 15000 miles versus the 5000 miles with the Rotella dino. According to my calculations the biggest savings will come from reduced fuel useage and, in a long-term viewpoint, reduced maintenance costs. The material pricing was taken off the AutoZone and AmsOil website. The AmsOil site has a very nifty feature that will show you every fluid that they offer for your particular application.