If you do not trust your refiner to use quality stocks and balanced additive package then either switch refiners or get a lubrication engineering degree so that you can build your own lubricant from scratch. Forget trying to "improve" formulated lubricants by using the shake and bake method.
Some people think that buying 91-92 octane fuel is a waste of money. They add mothballs to the tank. These folks enjoy close relationships and quantity discounts with the best machine shop and tank re-liners in the county.
for sale: 1968 R 69 S-us original condition