hi there, sorry Simon, im not doubting your profession abilities or qualifications etc but seeing as you work for castrol it is a bit predicable that you'll say their stuff is amazing.
what do you use in your S2000 by the way?
a mainstream dealer/manufacturer will use whoever they get the best rates with. sure its probably not a catastrophically bad oil etc but once the car is out of the warrenty period, its out of the dealer/manufacturer's hands and they dont care.
BMW as an example... you must have heard of BMW sludge issues
Yeah agreed, I am bound to be biased, bear in mind I see exactly how oils are developed too, if they were as bodged as made out I would certainly not risk it in my expensive engine. I happily used Magnatec in mine up until the last change. I am now using an SLX development oil.
I have not once said Castrol is better, simply educated some very wrong facts.
Chances are there's not much difference between all mid-tier products anyway. A few oils are known as market generals, this is a formulation that additive companys developed to be sold to the lubricant marketer (Fuchs, Shell, Mobil, Castrol or whoever). These don't offer anything extra over the competition (obviously) as they likely all have similar oils anyway.
Your right with independant dealers, however the OEMs do recommend what should be used to the dealers and in some cases the correct oil must be used. Just look at the VW PD engines, and of course DPF equipped diesel engines. The main thing to look at is the industry specs. I believe even GTX meets API SM though (the latest service oil for gasoline engines)
There is a lot of co-engineering work that goes on with Lubricant companies developing oils alongside engineers from OEM's engine development teams. Obviously can't say too much.
BMW recommend one company based on this sort of collaborative work, you'll see it on the oil filler caps.
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