I have the big 8qt milidon oil pan. I'm going to drop in the lucas hotrod oil at 20w/50 and use the rest of my brad penn 10w40 for top off. both are high zinc oils and have great reputations. I cannot see an issue, but time will tell.
Have read from this guy that sometimes mixing different brands reduced zinc levels because other additives don't always mix.
From report:
my Engineering tests of the Brad Penn, Penn Grade 1, Break-In oil, shows that it produces a film strength load carrying capacity of only 56,020 psi, which ranks it 187th out of 195 oils tested so far, and puts it in the UNDESIRABLE wear protection category, even though it’s high in zinc. And my Engineering tests of the 10W40 Brad Penn, Penn Grade 1, shows that it produces a film strength load carrying capacity of only 57,864 psi, which ranks it 183rd out of 195 oils tested so far, and also puts it in the UNDESIRABLE wear protection category, even though it has a high zinc level.
