The ability to hold upto degradation against the higher temps from track abuse and keep the engine well protected againt wear.What are you looking to note? Oxidation resistance? Wear resistance? Fuel economy? Deposit formation? Valve deposit control?
One notable (and informed) difference is the Motul product has actual Longlife-04 approval which demonstrates the oil's performance in all those areas.
If LL04 is the all important standard would I just be best off buying any 5w40 approved oil off the shelf? I can get 20litres of 5w40 Rock Oil “fully synthetic” for £44GBP from my local auto parts store but I was under the impression not all oils were born equal hence my question.