1989 300te...167,000 miles, rebuilt head (about 1000 miles ago). I seem to use oil...about 1 qt, every 600miles. No external leaks, plugs are clean. I use Mobil One 5-30. New York, cold winter.
Mechanic says that he NEVER uses a light weight oil in older engines...wants me to shift to a 10-50 Mobil one. Any thoughts?