Hi all, I’m just after a little help with understanding the differences in these 2 oils. See what I just can’t seem to find out is, typically what would be the differences that makes one oil a performance oil over a standard oil when there both, Mineral 20w 50’s SL rated An example would be, Castrol’s GTX 2. This oil is only for standard engines running under normal conditions. Pennzoil’s GT Performance. This oil is said to be for high horse power, performance engines driven under all conditions. There both: Mineral 20w 50’s SL rated You could even use two castrol products as an example. Again the standard GTX 2 and there Formula R 25 50. I know the Formula R is a bit heaver, but what is it, in side the oil that makes it better? When you get VOA done, there all simular in ingredients, so I just cant seem to find out what it is that is the different ingredient that makes it suited for high performance use, when there all neck in neck in available spec’s.