I don't believe any OEM says you NEED to, but its not a bad idea. Better fuel lubricity, keeps the injectors clean, and usually helps out the Cetane rating a bit for just a little more power and economy. I use Amsoil Diesel Concentrate every tank in both my diesel's personally.
Unless addressing an issue such as an algae growth or a gelling problem, you are pretty much wasting your funds. Have never found any diesel fuel additive that was worth the money and yes, I've run Standadyne and about any of the others you can name.
It says directly in my manual NOT to run fuel additive. Im with Gunny. Most of the time additive helps clean and lube the system. So it might be a good idea to run additive like stanadyne, lucas, or delphi ever 1000 miles but you wont see any immediate gains.
Thanks guys, I know I asked this before, but thanks again. Oh, yeah, what type of oil are you guys using? How often are you changing oil? I changed mine about 4300 miles ago, and used chevron delo. Planning on changing it every 4500-5000 miles. Could I run synthetic, and have no problems? Have about 8455 miles on my truck.
diesel nut is correct, this ulsd crap is killing mileage and lubricity
amsoil 15-40 full synthetic, and wait until 10,000 miles to change over then 7500 intervals to change for me but it is personal preference. Look at it this way, you paid 45,000 for this truck why put crap dino oil in it? spend an extra 25.00 an oil change plus change intervals are a little longer.....just my two centavos
oh yeah and it says not to in the manual because they want your shit to break and you will have to come to the stealer for repairs or a new truck..
On your LBZ CLassic you can actually run 15k oil changes with Amsoil. More often if you like, but the oil is actually good long beyond that with analysis and bypass filtration. That is a little more work than most guys want to mess with, but it is an option.
Amsoil rates the Diesel Oils (excluding the DEO 5W40) at 25k miles regular service, 15k severe service. Almost everyone qualifies as severe service, just by the nature of our trucks.
As for mileage claims using additives, its all relative. I have had customers tell me 2+ MPG, and had some tell me none. No one has told me of a drop in mileage. Mileage is so hard to pin down due to the variables.