Stank smell could be some sort of sulfurized additive, more common in gear lube. On sheet 13 of the SDS (across grades), Pennsylvania right to know contains a line item for an Afton Chem HiTEC 11188 - 000000276110 PROPRIETARY. If you search the Afton website, you can find 11180 (ILSAC GF-5, D1G2), and 11181 & 11183 (D1G3 add packs). 11188 produces no results.
Anyone with industry knowledge, could this point to a unique additive technology for Valvoline?
Edit: or possible it has similar chemistry, albeit less aggressive to premium blue restore and uses the technology of Valvoline patent US20170029734A1