I'll be getting a used motor soon for my Subaru. It will most likely have around 50k miles. But has been sitting for who knows how long. My plan was to run xxxxx oil for xxxx miles then switch to rotella t6 for 5 k and get oil analysis.

Question, what steps should I take for new motor? Old trick of spraying marvel into cylinders before starting? Do I use a cheap supertec oil first? How long should I run it? Thank you
2012 Hyundai veloster 6speed 115k and climbing
2002 Subaru wrx wagon auto 220k
1988 Camaro waiting for powertrain...