The owner's manual calls for 91 octane on the 2.6 6cyl.

What does "conventional wisdom" say??
Tks,
C

Depends on your ambient temperatures, altitude, and driving habits.

I only drive my 2.6 in the Winter and Spring months and it's okay with regular unleaded as long as I ease on the throttle after a short shift. Otherwise there might be a bit of transient detonation. No sustained detonation. I recall back when I drove it in hot weather with the AC on I could occasionally hear some transient detonation on unleaded premium.

You have to experiment to see what works for you and your engine. Start with a near empty tank and try a few gallons of 87. If you don't get significant detonation try some more when it gets back down to empty. If you get signficant detonation add some higher octane to the tank. If it won't run on a pure diet of regular, it might run okay on midgrade.

The specified 9.2:1 compression ratio is not high and many engines with CRs up to 9.5 and no detonation sensors run fine on regular.

Duke