^ I think the price difference is greater for me. M1 costs about $25 for 5qts, but it looks like redline is around $50... so the difference would be 120 qts x $25 = $3,000. Over the life of the car - not earth shattering I guess.
Also saw this post which was interesting :
Oil Nerds Info
Making me consider the Castrol more and more... although I don't think either one will really eff your car up if you check and drain it regularly.