It's BG 44K. Best damn stuff on the planet, IMO. I use to use this in my other car about every 10-15K miles to clean everything out. Well, I didn't realize just how great it was until now. As you all know, the timing was off on my X for a long, long time. Figuring that I had carbon buildup as a result and that was the reason behind my excess engine noise and power loss (or so it seemed), I decided to try the BG in the Xterra to clean things up. All I can say is WOW!!! After 1/2 tank of gas I have a noticeable increase in power and reduced engine clatter. Seriously, my engine runs and sounds sweet...almost like the Nissan engine was yanked and someone dropped a BMW inline 6 in there. Well, maybe that's a bit exaggerated, but it's quite a bit smoother and better sounding. I also expect an increase in gas mileage, but I won't know for atleast a week after I fill up and drive normally on the next tank.
BG 44K is a professional grade fuel additive and not available just anywhere. I get it from my European Car specialist here in the Seattle area. Cost is about $22 per can, but well worth it. I highly recommend it's use on an occasional basis even if your truck seems to be running fine. My mechanic puts it in his Chevy truck every 5K miles. I'll try and get a phone number or something so you guys can track it down locally if interested. If anyone wants some and can't find it, I may be able to arrange something too.
Anyway, I'm totally sold on this stuff and am only posting my experiences. Maybe somebody else will think they have lifter noise or whatever and it's really just carbon buildup that can be removed by the BG 44K.
later!
Here's a link for an online retailer!
http://www.webertransmissions.com/order.html