Guys, I have 255K on an 81 300SD that I have had since 1984. I have always purchased the cheapest diesel I could find, have never used Redline, never added cetane booster, have never had a fungus problem. I have always gotten around 20mpg overall and maybe 24-25 on the expressway. I finally got the valves adjusted about six months ago at 250K miles (first time since 1984) and all it did was make it easier to start. About three months ago I started using an additive to make it smoke less; I think maybe it works some but I do not have too much smoke anyway without it.

Would be hard pressed to believe there is any difference in diesel fuels whatever the source; just have not seen any difference. However this is just a personal view with absolutely no science behind it.