3 quarts in 2k miles is high but not horrible.

When the valve seals were replaced were they sorted as intake vs exhaust and definitely installed on the correct valves I.e., intake vs. exhaust?

The oil control rings may be gummed up, I’d try a chemical soak on the rings. Has a compression test been done?

For oil I’m not saying the oil you are using is wrong however I’d try a diesel rated 15w-40 such as DELO or Rotella non-synthetic.

Good luck!!!