I've used it for years, along with howe's and powerservice in the winter. Redline makes good stuff and I'm a big fan of their products, but I got better results in my 5.9 with the fleetguard additive during the winter. This winter was mild so I had no gelling to worry about here, but I tried the redline winterized stuff and the fleetguard addy, and I had noticeably less smoke and diesel odor on cold starts in the morning with the fleetguard. All of those additives make a difference on my lie-o-meter so I'm gonna keep using 'em. I'll stick with the redline stuff in the warm months, but I'm staying with the fleetguard for the winter-that includes the truck, the genny, and the snowblower, all of those being diesel powered.