Post by
BrianV »
https://forums.nicoclub.com/brianv-u33653.html
Sat Feb 09, 2008 4:16 pm
Chalk 1mpg up to coincidence. You should not see reduced MPG from going up in octane.
I REPEAT, the ONLY difference between regular and premium is the octane (Shell's VPOWER also includes added detergents, but Chevron, Texaco, Exxon, etc are all the same with the exception of octane).
Octane has absolutely ZERO affect on an engine and its performance UNLESS the engine would knock on the lower octane forcing timing retardation. If that happens, then one could confidently argue that running regular instead of premium would REDUCE mileage, but again this is only if the engine retards timing to avoid knock. The 2.5L I-4, Nissan's workhorse, economy 4 banger DOES NOT require premium, in fact I bet it'd run fine on 85 octane even at sea level. The VQ35 is a different story, but the Rogue engine was designed to run on total junk and be economical and reliable.
Putting premium in it is a complete waste of money.
My recommendation is that you just buy a top quality regular unleaded. One with good detergents in it. The good fuels do work at keeping carbon deposits down. By time you get to 75k miles there's a huge difference between an engine running Walmart gas and one running Chevron.
I'd say Chevron and Texaco offer the best regular unleaded gas. Just stay away from grocery store, walmart, sams club, costco, off-brand, etc. It'd be fine for a few tanks, but make a habit of using a high detergent gas.