First thing first...congrats. The GU is one of my favorite trucks. -How often do I need to regen? - see below -How long does it take to regen? - see below -How often to service the filter, and is it a big job? - 250K miles -Can I regen anytime, or do I have to wait for a warning light or something - regen will occur only when needed. -What happens if I interupt the regen process? My first suggestion is to make sure you know how the smart switch works and what will happen in each position. It needs to be in the up or nuetral position. The down position is also know as the inhibit position (some truck so not even have this option). The only time you should have it in inhibit is when you absolutely do not want to fire off a regen (going inside a building or anywhere that high exhaust temps could cause damage to your surroundings). Putting the switch in inhibit will also limit your speed to below 15 mph. If you notice the truck will not go over 15 mph or will not get out of 2nd gear (for an auto shift) double check the switch. I've seen way too many trucks towed in for this very reason. The regen frequency depends on driving style and driving conditions. Basically how quickly the DPF filter fills up with soot.Regen times will vary as well depending on what level the system is at and how full the filter is. You basically have 4 levels. Level 1. Your Blue DPF smart switch will be lit with a steady light on the top half of the switch. This will let you know that a regen is needed. You can simply press the top of the switch for a few seconds to start a regen or you can do a parked regen if you like. Parked is not required at this point. Level 2. Your Blue DPF smart switch will now start to flash. from here it will be the same as level 1. you can run a parked regen if desired or simply press the DPF switch while driving. Level 3. This is am important level. This is the last chance that you the driver have any inpout on what happens. The DPF switch will now start flashing and you will also have the lightning bolt on the dash. At level 3 you MUST run a parked regen. With the truck running, you need to make sure the cruise is off and the parking brake is set. Once again make sure you are not parked under anything that your high exhaust temps could damage. Press the top of the smart switch. Level 4. Once you are at level 4 your are in trouble. You cannot run a regen on your own and it will have tp have a service regen run by the dealer. The DPF switch will be flashing, and you will have the engine shutdown light on. Now when you are running a park regen you press the smart switch. The engine will idle up, and as your exhaust temps rise the HEST light will come one. This just lets you know that the truck is regenning and the exhaust temps are very high. A park regen can run 30-60 minutes depending on your soot level. Once the regen is completed the truck will idle back down. The Hest light will only go out once exhaust temps drop. You do not have to wait for this to happen to drive. Driving will help it go out quicker. This is the short version. Keep in mind this is for the DPF units that are located under the passenger steps. If you have the back of cab version on an LE or MRU some things will be different. These trucks will not idle up during a regen. They idle at 700 RPM instead of the usual 650. They have a fuel and spark source in the stack itself to handle the regen ignition. This should be enough to keep you out of trouble. if you have any more questions you can feel free to send me a message and I can send you some stuff that might help. You can also call Mack One Call 800.866.1177(breakdown assistance) and one of the guys can answer more specific questions. I know this is longwinded but believe me when I say there is more to it. Eric
