Engine pinged with regular gas

[MoonRivertttt]

My 07 G35 MT had slight metallic rattle sound as on my way from FL to WV, it happened as I passing Charlotte, NC, on I 77. It wasn't hot out there, about 60,70. I right away got off the inter state, topped off with premium gas, it took about 1/2 tank ( the other half was 87 regular). It didn't improve. Then when it claimed up the hills on I 64 near Charleston, WV, It became worse. It got better as I down shifted to 5th gear. The engine only had around 45K miles, and it wasn't carrying too much weight, just myself about 120 LB and a luggage of clothes. I have been filling 87 octane.

I am planning to pull out some spark plugs to check if it's running too hot.

[SVTCOBRA]

Based on the manual, coupes require prem.
Your experience does not surprise me in the least bit based on my experiences with the 3.5 engines in my past and present Infiniti's.
I do know that you can get away with a lower octane with a manual transmission.

[audtatious]

Try resetting the ECU and running a few tanks of premium to see if that resolves the issue.

[Warpkor]

I've got the 6sp MT, too and never had much luck with the lower calorie fuels. I'd get pinging at any speed, load or circumstance. Pretty much use premium all the time. I did swap out the plugs at about 100k miles and they were completely baked.

[SteveTheTech]

I do not know that I would recommend resetting it. The cars programming is set to (ideally) run on 93 but over time can adapt to fuels with higher resistances to burn (lower octane) and it probably takes a thousand miles to relearn its new fuel.

If you do not plan on running premium I would replace the plugs early. I do not know if you would want to go hotter or colder (maybe one of the turbo guys here would know).

This is a common occurrence with this engine and transmission combination, they can get really loud at high load low rpm situations.

[jmann]

The cars programming is set to (ideally) run on 93

Is this right? For some reason I have always thought it was 91. 93 isn't even sold in a lot of places. I have been mixing 93 and 89 to save a few $ but always use at least 91. If I might get better performance out of running 93 I might not even bother with that...