The six speed is an AWTF-80SC, which uses a different spec Exxon/Mobil after 2010. From 2011 it's a JW3324 which is very different to 3309. The Brookfield at 100C is 5000 points lower than 3309 for starters. The Valvolene is much closer in spec to 3324. Brookfield is about 1000 points higher although (oddly) the Viscosity Index is slightly lower.
I recently read an article whereby test studies were carried out on modern low viscosities that indicated a lower wear factor was experienced with the lower viscosity oils, but for me the jury is still out. I think I'd need to see a bit more evidence to support that. Time will tell I guess.
