Originally Posted by Reverendbiker

Actually it's just the opposite--the higher the octane the more you are able to ADVANCE the timing. The 2005 Frontier owner's manual states that the minimum fuel requirement was 87-octane but higher octane could be used for increased performance. I only ran this test to see whether this engine made significantly more power on 93-octane than it did on 87; my (admittedly unscientific) dyno test indicated that it didn't. Since that time I have used only regular unleaded fuel and my engine runs happily on it.