Adding 2-stroke oil to gas?

Bad idea. While it will help save valves on old engines those manufactured back when gas had lead in it, it wont do a thing to help modern engines. and it will over time foul the catalytic converter, and foul plugs. Consider we changed plugs every 12,000 miles back then compared with many letting them go 100k today.

Whitelightning

I'd have to wait and see what the other folks say. My first impression is not much change. In a two stroke engine, the crank case is bathed in gas oil mix vapor. On a four stroke, only the piston and intake area is exposed to the vapors.

My wild guess is that you'd do better to use only Castrol motor oil, and observe your oil change intervals.

My last truck had a nasty piston rod knock. Warmed up, and at idle. Thunk, thunk, thunk. Castrol was the only brand that quieted the rod knock for more than two or three days after an oil change.

I get that mileage without the oil. It can't hurt, but I don't think you'll ever see any gain.

Stupid on a newer engine. Just change the oil and filter every 4k.