08SSTCRD

The real issue here isn't brand, its the actual formula, and its only become a problem over the past few years due to new API standards.

In simple terms, manufacturers/API have decided that higher levels of zinc (ZDDP) and phosphorus in motor oil are not conductive to long catalytic converter life and clean emissions. Both elements can coat the catalyst if the engine consumes too much oil due to PCV issues, blowby, wear, ect. over the course of its life.

Unfortunately, these two additives are what allow for engine oil to lubricate moving parts without scuffing/damage in the absence of hydrodynamic lubrication. Which basically means they prevent metal-to-metal contact of the rod and main bearings to their journals during startup and in the event that oil pressure is temporarily lost. They also protect cam journals, rocker arms, cam lobes, valve guides, and lifters, which often do not have any form of hydrodynamic lubrication - these parts are typically splash-oiled, meaning oil being pumped around the engine creates a film that prevents the metal parts from wearing into each other.

Which leads us to the problem at hand - with the elimination of ZDDP and phosphorus from almost all major synthetic (and conventional) oils, the chances for mild to severe internal engine wear go up substantially. Engine oils are designed to prevent metal parts from touching by forming a barrier between the parts, such as in a rod or main bearing. The journal "floats" on the oil above the bearing, so in theory, the bearing should never see any wear. Unfortunately, if this barrier is broken (oil loses its film strenght over time) the parts will touch, and with no additives to shield the surfaces from each other, severe wear can and will occur. This is especially true with OHC valvetrains, in which the cam lobes are in direct contact with a rocker or lifter surface and the only thing between the moving parts is a thin film of oil.

As some may know, a few high performance oils still have higher ZDDP and phosphorus content than the maintream brands, mostly because they don't sell directly to manufacturers and they don't sell the volume that the major brands do. Two of these companies are Royal Purple and Amsoil.

Here is a Royal Purple experience from a 3V 4.6 Mustang, I discovered this thread when it was linked from another Mustang forum:

Mustang 3V Royal Purple Difference

For any high performance engine, I would strongly encourage looking into an oil that still uses higher PPM of ZDDP/Phosphorus.