In my experiences, any oilbrand is quite okay to use, special formula? Well, point is that it lubes... On a high performance output over distance, or a supertuned engine on 100% performance, as a rallycar,dragster or similar,then it could be a question of how good it lubes.. On a normal use motor, not supertuned, it normale use approx 5% of using time (on a car motor) at full performance, a engine as yours use perhaps a little more, but not much.. Everyone if checking for shure use different oilbrands, also on this forum, but does the engines of ours get ruined because of that?
The crucial is the measurements....could one be so good, it can use a little less of it? Dont se so big trouble, test it out with the producers recommendations, and if you feel not, use a higher ratio, or if the stomach feel says other, use another brand.
I have friends using standard cheap motoroil on 30-50s car engine in 30y. now, no lead substitute, and the engines has no trouble, no extraordinary wear than others,and is as good as anyone elses who use all different additives, and high,superduper oils.....And valveguides are the original ones, who everone says gonna be destroyed without lead substitute.