Originally Posted by GraphiteGhost

Here in SC the have 87, 89, and 93. The XF says it needs 91. So if the car can adjust up two octane ratings, why not down 2 at 89 octane. Thats what I run and its quite a spiffy lil car. I would not go down to 87 but there are a number of folks who are running regular (do a search on octane). Here in SC the difference between 89 and 93 is almost .20 cents so it makes a little difference. Where I will not compromise, is oil changes. Have to use Mobil1 0W-40 at each change!