My owner's manual for the 07 TL indicates that 91 octane is
"recommended" (not required) for best performance, and that octane
below 87 will damage the engine.

Is anyone using below 91 octane on a regular basis? If so, how does
performance/MPG differ?

Reason I ask is that a Lexus salesman told me that Lexus "recommends"
91 also, but many of his customers run 87 with no problems or decline
in performance, and that it will not void warranty. I suspect it will
not void Acura warranty either.

 

89 here no problem... is not like im at the track all day, no clunk sound nada and i have a 04

 

with a followed by concluded with


11:1 compression ratio...

If you search for this issue, youll find it discussed to death, and conclusion yields, You should use 91 octane...

 

Exactly. To the OP, please do a search for this topic as it has been beaten to death. Thanks.