I use Mobil 1 15w-50 in my Paxton supercharged (flat tappet) 289. Been using it for 22,000 miles now, no wear, no leaks, no problems. It has 1200 ppm of zddp, about the most you can get w/o going to a racing
oil or the Mobil 1 V-twin
oil (1600 ppm zddp).
http://www.mobiloil.com/USA-English/...1_15W-50_.aspx
http://www.mobiloil.com/USA-English/...t_Engines.aspx
Z. Ray