This by the way is a general turbo thing, not just JGC Turbo Diesel thing. A turbo can spin at 100K RPM or more. They also generate lots of heat. When the engine if off, oil doesn't circulate around the bearings in the the turbo. This can cook the oil, leaving behind an sticky residue, which collects dirt and becomes abrasive. Over time this wears on the bearings causing failure. By idling before shutdown you allow the turbo to cool down and prevent the cooking of the oil. So before shutting down try to keep the drive before the shutdown easy. I do things like get my postal mail with engine running that counts towards the cool down.
It's one thing that I think Jeep missed in their design. There's no way to monitor turbo boost, nor turbo, EGT, temperature. It's something I mentioned repeatedly in the online survey they asked me to fill out. Allowing you to determine how long you need to idle before shutting down. I've E-mailed Gale Banks and they will be supporting this engine as well. Hopefully, all the needed info about turbo boost, temp will be available via the ODBC II port. If not I'm looking into an A pillar gauge cluster with that info. Alternatively, they could delay the actual shutdown automatically until the temp drops or use battery to run oil pump to circulate oil and water pump to cool it down quickly.
The Turbo in the JGC is water cooled by the way. So I would expect that under normal circumstances you won't have to idle it for very long. But its cheap insurance if you plan on keeping it after 100K.
It also brings up the point, changing oil / filters is critical to engine and turbo life. I'm not really liking 15K intervals. I haven't fully decided but I'm leaning towards 7.5K miles instead, or 10K at the most. Yes, it's more expensive but I think its worth doing. Good time to rotate tires and have a general inspection done.
