Posted: Dec 08 2007 at 3:23pm | IP Logged

hsckris,

i took a peek at the website you posted for the owner's manual, and it does say something about 87 octane (AKI) being the recommended fuel, but that is differentiated for the 2.5L 4-cylinder engine. Just underneath that the 4.0, indicates they recommend 91, but if not available anything with AT LEAST 87, but that a decrease in performance might be noticed.

if this still doesn't clear things up and someone's manual indicates that 87 (regular) is recommended for the 4.0 rather than the at least 91 that this stated, then perhaps we can still shoot an email to Nissan NA, however i do find it interesting that on www.nissanhelp.com it states recommended fuel is regular for the 4.0L as well. That might be bad information as far as Nissan is concerned, as I stated before, makes me wonder if it is affiliated with Nissan.

Posted: Dec 08 2007 at 4:48pm | IP Logged

Frontyfan, thanks for the additional information and clarification.  I should have thought to put that in my response.  My apologies for a terse reply.

Nevertheless, I am curious.  Has there been any evidence (long term) of damage to the 4.0L engine by running it constantly on lower octane fuel?  I know from my own experience over 45 years of driving that serious engine damage can occur such as burned pistons, valves and valve seats.  Today, with induction hardening of the valve parts, this may be minimized but I would still be worried about burning through a piston.  Interestingly, the octane rating posted on the pump is an average of "motor" octane number and "research" octane number.  Usually and necessarily for good performance, these are withing a very few points of each other.  However, in Europe some years ago, they apparently had some fuel on the market with a low motor octane rating and a higher research rating.  This caused severe engine damage problems as the low motor octane (real world driving type number) was causing piston damage.

Posted: Dec 28 2007 at 9:51am | IP Logged

I've got 57000km on my 06 fronty and have always run 87.  I tried running 94 for a full 5000km and did not notice any increased full economy or power gain.