Originally Posted By: Triple_Se7en
From what I've read, Petro Canada 5W-20 may be the thinnest.
Nope, it specs out at 8.6 cst at 100c, so it's not the thinnest.
Formula Shell 5w20 is a lot thinner, it's 8.16 cst at 100c according to the PDS. That's one of the thinnest commonly available oils out there. I recall one of the "boutique" synthetics was under 8 though, but I can't remember which one. It wasn't a commonly seen oil though, that much I do remember.