As with most topics on this forum, I wanted to get my 2 cents in. I hope my frequent posts are somewhat helpful to the rest of you.
I go to an independent diesel servicer, Orangevale Diesel, in the Sacramento area. I asked the owner about diesel additives, and he told me he uses Petrolabs
Diesel Power Plus. Besides doing a great job at cleaning and protecting the engine fuels system, you only need to use 1 ounce for 32 gallons of fuel. A bottle (16 oz. measuring bottle) costs around $10. That's less than 2 cents a gallon of treated diesel. My mechanic told me that he had a guy come around with new diesel pollution measuring equipment for sale, and they tried it on the mechanic's 7 year old truck in which he had been using the
Diesel Power Plus. The equipment could not measure any appreciable air pollution from the truck.
The bottles I get from Orangevale Diesel have "Petrolabs" marked on them. The Petrolabs website has "Diesel Power" additive listed, but not "Diesel Power Plus". Their website has several areas "under construction" that have not been updated in 2 years. Searching the term "Diesel Power Plus" got me to a website for Xtreme Diesel Performance, which sells Diesel Power Plus for 8.95, and it treats 32 gallons of fuel per ounce of additive. I called and asked about the Petrolabs/Extreme Diesel relationship, and the guy I talked to had no idea about it.
Here is a link to the Xtreme Diesel Performance webpage on Diesel Power Plus:
http://www.xtremediesel.com/xdpdieselpowerplusfueladditive.aspx
Here's a link to Orangevale Diesel (Hint: Most 5er owners will LOVE their homepage pic!):
http://orangevalediesel.com/index.html