Something that is not intuitively obvious is that the Mobil racing
oil in 0W-50, like Morris uses, has among the highest ZDDP levels of any
oil you can buy today. I believe the numbers are 1300 ppm possibly higher. This is very good for flat tappet cams and lifters.
Most of the oils once you get to the 0W-50 threshold will have higher ZDDP levels. FWIW (and it could be a lot) Mobil 1 seems to be the highest. Castrol used to offer a 0W-60 high
zinc oil for super car applications but I haven't seen it for a while so the 0W-50 oils (especially Mobil 1) get the nod.
If you want to be certain research their
zinc levels before buying. If the 50 and 60 weight viscosities leaves you a little timid, Mobil 1 also has a 0W-30 Racing oil with the same
zinc levels in it.
Ed