M1, as an early market entrant/developer, put the price umbrella under which most motor oil companies could price. Of course they got the best price.
Along comes GrpIII with substantially lower production cost and performance 'near' that of Grp IV. At least in the US, GrpIII could be labeled 'synth'.
Then you had M1 pricing based on GrpIV but competition able to market GrpIII pricing 'near' GrpIV. Companies like Shell could smell blood...'near' GrpIV pricing with much lower GrpIII production costs.
In steps Marketing. Hey, Gross Margins of GrpIII can be really high... lets build Brand Awareness (later Loyalty)...uh, best way ? Deep Discount to people "in the know", A.K.A. virual marketing (First Driver program is best example.)
Marketing: What we lose on promotional cost we more than make up in profits later ! Hence PP, QS, Valvoline synth for $1-2/qt.
BUT WAIT, it Works ! I have spent more valuable time analyzing and recommending these products than all the free/disocunt oil I have gotten. Key element is the stuff delivers.
I know I'm getting deep discount/free oil but I'm spending time finding the best way to take advantage of the opportunity.
All of this in not lost on Mobil. Quick switch to GrpIII and selective holdout (such as 5W40 European) to keep cache'. The issue as I see it now is Mobil GrpIII not as good as Shell XHVI since Shell focused more R&D on GrpIII.
Last point. PP seems to follow the Shell line (such as add pack) while QS is doing more marketing (how many Q-xxx ?) and formula tweaking. That's great. More options (weight/promos/rebates) for me to choose from.
I could keep going about Conaco and Valvoline with Grp IV strategy but enought for now.
Gotta' Luv Free Enterprise
Gotta' Luv Grp III
Opinions expressed here are my own opinions, which have may little resemblence to reality.