I will just talk about the majors, and in the Heavy Duty Trucking market, we will just call them the big 3, Shell, Mobil, and Chevron. Three of the toughest competitors there is. All three want the others business. Each uses a different additive, but all are close. All three own their on chemical/additive company and they are good. In their standard premium grade of 15W-40 all three use Group II+ base stocks, and all three perform extremely well. The customer base they cater to do not care about promotions, rebate gimmicks, etc., the customer base cares about three things, performance, service, and what's it going to cost.
Then you have the next tier of HDEO makers like CITGO, ConocoPhillips and all their brands, Castrol, etc., and then comes the speciality oils like Schaeffer's.
The customer wants the same from all of these. Performance, service, and how much.
To make a quality product without charging an arm and a leg for it you have to eliminate something, and that is marketing. Now they do their fair share of advertising in trade journals etc., but you won't see them on TV or a major sponsor at some major race, or sponsoring the Super Bowl etc. What major oil companies spend on marketing their line of PCMO's would boggle your mind.