Welcome aboard.
The idea of using the exhaust brake all of the time is to keep the sliding nozzle free of soot. When it no longer moves freely it will require cleaning. IMHO, cleaning leads to turbo replacement. I have 35,000 on mine with no codes and great performance, the only upgrade I have done is a K&N replacement filter element that I bought last week, it is the same price as the paper replacement, about $75. The jury is still out on the K&N though, I will be watching for dust infiltration into the intake tube. I, myself cannot complain about the "fuel" mileage, most say it is poor but I used to drive a 96 with the V-10, so anything over 10 MPG is great!! Drive it, use it like a truck, service it regularly and you should have many happy miles to go. As far as the Amsoil, I have heard good about it but I feel that for the cost you would want to add some type of bypass or High Effiecency filter system to it. I run Valvoline 'blue' their synthetic oil and change it at 5,000 miles with oil samples taken, so far no issues and looking to extend out to 6,000 miles.
Good luck and Enjoy.

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07.5 3500 Quad, SRW, 4X4, Laramie, Leathered, Dark Metallic Gray, 6.7, 68RFE, 20K Reese, Ride Rite's, 2 Viair air compressors, Bully steps, Kleinn Locomotive air horns (5 in all), Billet polished locking fuel door, 'A' pillar mount Auto Meter Pryo, PML X-deep trans pan
06 Durango 285 RL 5'er Lifted by KZ