If Redline's HTHS spec can be believed (and I don't think it's right), then Redline's 5w-20 is the thickest with a HTHS of 3.3 cP. I believe Mobil1's 5w-20 is thinnest with HTHS of 2.62cP.
quote: Originally posted by Buick92: I was wondering which 5w-20's were the thinnest and which were the thickest? I thought Castrol GTX was on the thick side, what about Chevron 5w-20?