don't use stop leak. find the leak and fix it. With your 3.0, most popular oil leak locations are the valve cover gasket and the OFHG. You have a ton of miles so i'm assuming that both gaskets haven't been changed ever, or in a long time, which makes them both prime culprits. The dealer couldn't figure out where the leak was from?

FWIW, i've only heard of one main seal leak on our cars, and thats from an X5 that was abandoned for 2 years.

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2018 Ram 2500 6.7L Cummins 68RFE
19k miles -Bright White/Black - Big Horn Sport - Crew Cab Short Bed
2013 X5 35D (CEO's) - Born on 5/17/2013 -
82k miles - Alpine White/Cinnamon Brown/Premium Pkg, Sport Activity/Premium Pkg and Sound/20" Style 214/Running Boards