Any big difference between synthetic brankds say Quaker state and Mobil 1?
There are a lot of opinions about this, with some people saying that the differences are insignificant, and others claiming that they matter. Note too that there are now some brands that sell more than one grade of full synthetic, such as Pennzoil (its Pennzoil Ultra is a higher quality than Pennzoil Platinum) and Castrol (its Edge with Titanium is a higher quality than its Edge with Syntec). One can only guess that they introduced higher quality versions, at higher prices of course, in order to compete with expensive specialty brands like Amsoil, Redline, and Royal Purple, which cost even more money.
My personal opinion is that (a) there is a much, much bigger difference in quality and protection between any major brand of full synthetic oil and conventional oil, than there is between any one brand or version of full synthetic oil and another, and that (b) the slight differences between one synthetic and another may matter on a race car used in competition, but on a passenger SUV that is only used for everyday transportation, not so much. So for me, I'm perfectly happy using a less expensive major brand of full synthetic oil like Q-Power (Quaker State) or Pennzoil Platinum rather than Mobil 1.
I'm sure there are those who will disagree and tell you that a more expensive synthetic is better and worth the extra money, just as I'm sure there are those at the other end of the spectrum who will disagree and tell you that conventional oil will protect your car just as well, that it's not worth spending extra for the advantages of synthetic. And for all I know, either opinion may be just as valid and knowledgeable as mine. It's one of those things like religion, where lots of people have lots of opinions and you just have to decide what to do for yourself.