My 2.5 with 273K miles has been burning oil, I was told upping the thickness would be good, so have been adding Mobil 1 15w-50, synthetic.  Someone said that conventional oil may be preferable on high mileage cars.   Another piece of advice was to use Rotella 20w 50.  Anyone have an objective analysis on the right oil to use?

First question is were is it burning oil from, past the piston rings, valve guide seals.....

Don't know that's worth doing a leak down check, but that would provide some answers.

How much is it burning?

Is it burning it or leaking it?

It's burning, most likely the part of the engine that is hard to reach.

I have used  lucas engine oil stabilizer in the past and it has helped tired motors.

 

I have even put it in with 20-50.  If it is cold out then go 10-40 or 15-40.

  read the lucas bottle. you don't have to put the whole thing in....

Getting a little harder to get conventional oil around here...