Hi Pat O., I realize that your post was almost seven years ago, but I'm interested in the results of your followup test and whether you believe that any significant damage was done to your engine by the SMB / Amsoil filter system being plumbed backwards by SMB West's apparently widespread installation blunder? (I'm a newby to the forum,.. Please read my post on page 14 of the "John and Dana" original "Amsoil warning" thread for more background) My 2006 6.0 L diesel was most likely exposed to 25,000 miles of this reverse-pumbed condition,.. perhaps as much as 15,000 to 19,000 miles of that may have been on the same oil (no records of what oil changes, if any, occurred before I bought it), and I have put 5000 miles on a new change of Amsoil DME oil and a new set Amsoil filters but with the hoses still backwards. I am totally disgusted with the lack of integrity of Sportsmobile West,.. that they didn't check for their installation error and correct it (or at the very least notify me of the issue) when I had the van in their Fresno shop in 2012 at about 19,000 miles and while I was paying them $3600 for other service and installations. I wonder how many Sportsmobile owners are still driving around with backwards plumbed SMB / Amsoil bypass filter systems, getting little or no oil filtration, and don't know it? If I hadn't had the recent CEL event and stumbled on this great forum looking for answers, I would still be happy and dumb, putting more miles on the rig with a defective oil filtration system. What is the hindsight consensus after several years regarding how bad this situation has been for longivity of our 6.0 L diesels?