I just started an experiment with the sister vehicle (same year, similar mileage, same engine, same fleet and same maintenance) of the vehicle that I ran HPL 4.3L GDI silverado and got a bunch of carbon material in the filter after running HPL.
So for this 2nd vehicle it had 190k miles, and lives on dealer and instant oil changes its whole life always followed maintence minder you can see the varnish in the drain hole but no sludge. Internals look similar as the HPL vehicle.
Instead of running HPL I am using RISOLONE and will cut the filter open at the same 3K miles to see if there is any carbon. I am using the same oil(RGT 5w-30) as I did when I ran the HPL.
Vehicle has 500 miles since experiment started.
So for this 2nd vehicle it had 190k miles, and lives on dealer and instant oil changes its whole life always followed maintence minder you can see the varnish in the drain hole but no sludge. Internals look similar as the HPL vehicle.
Instead of running HPL I am using RISOLONE and will cut the filter open at the same 3K miles to see if there is any carbon. I am using the same oil(RGT 5w-30) as I did when I ran the HPL.
Vehicle has 500 miles since experiment started.