Jeep 4.0L - which really was a American Motors based on General Motors inline 6 - someone posted the history here a while back - was a great engine that would go 400K on whatever ancient slop you find in the back of the garage. So it really doesn't tell you anything special about Supertech - either way.The 410K Jeep 4L on Supertech does say a lot about Jeep 4L, but also Supertech, IMO. We know it's a good design of engine, but we also know the oil was adequate. Maybe better than adequate.
Perhaps with a better oil it might have gone 500K. We'll never know.
Nissan VQ40 - 4.0L V6 - also great engine. Mine has 414,000 now on whatever conventional or blend I could find for cheap. I believe I ran Suptertech once because I found some in the clearance section but mostly cheap branded conventional. So some engines just run forever. Here is under the valve covers at 395,000 https://bobistheoilguy.com/forums/t...vers-395-000-miles-nissan-xterra-vq40.376175/