There is NO "91 octane requirement" read the manual, it is recommended but it is designed to run fine with 87 octane. It won't affect your warranty either because is written in the manual in plain English. use a Moly-additive to help with rocker arm noise (which I don't think has anything to do with 87 octane gasoline)I’m aware of the requirement to run 91 Octane, however my Fuel Card w/ employer does not allow for premium fuel use. I’m just under 14k miles & have been using premium fuel prior to recent gas card issue. The reason for my post is I’m concerned w/ the “knocking” when she is warming up in Park - most mornings the garage is about 50F-60F. My ‘12 developed rocker arm issues & I’m concerned for not tearing up this engine. Btw, engine oil life is 56% at 3,500mi since last change. Will likely chg oil before 5k. Thoughts on workaround for 87 octane if any (additives)?