Premium gas makes it work better!?

VanillaXT

Test Drive
Location
Oakdale, MN
On a whim, I decided to put in a tank of 93 octane premium gas (BP branded station that just recently changed from Shell) in my 2015 Xterra. I couldn't believe the difference. On the regular gas at the same station (87 octane), it worked "fine" but it had a big lag in acceleration at a certain point. Once I was at a steady speed with the regular gas, I needed to add a LOT of throttle to get it to move off of that speed. Since I'm new to the Xterra, I thought that was just the way the engine was set up. Surprise! The premium fuel has mostly gotten rid of the issue. But WHY?

It's winter here in Minnesota, so did the regular gas have a poor additive package, more ethanol, or more water contamination? Does my engine with only 55k miles actually need premium fuel. The car was not driven very much before I bought it, and may have sat for long stretches. Could the engine have had deposits in the fuel injectors, valves or intakes that were removed be the premium additives in the 93 octane?

Has anyone else tried premium gas? If so, what was your experience?
 

Muadeeb

Nissan al Gaib
Admin
Location
Dallas
Do they like premium, well maybe. I ran my Gen 1 with it for about a year, tracking mileage and m/$ and it was about a wash. Do what you will.
 

meisanerd

Need Bigger Tires
How much ethanol are they dumping in the gas? I've tested a couple different stations with the same octane, but different amounts of ethanol in it, and less of that made more of a difference than switching octane.

I personally run the 87 from a decent station, going above that I dont notice enough of a performance difference, and the mileage gain to price difference usually comes out either the same, or worse than just using lower octane gas.
 

SyrusOO

Test Drive
I also have a Pathfinder with the tow package same VQ40DE engine and it states on the fuel door "Premium fuel is recommended for maximum performance for best performance". I can't attest that the tuning might be different but same engine and runs on all fuel types but tows better with premium fuel for sure.
 

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TerryD

Total Tease
Supporting Member
Location
Covington, Va
I've heard that the Pathy got a more aggressive tune to make the extra power numbers on an identical engine.

My Xterra VQ40 likes mid grade but doesn't see any gains from premium vs mid grade.

Mid grade is literally regular and premium mixed at the pump for like 10% more. Just put a half tank of each or alternate fill ups between one and the other, opting for premium if the tank is less than half full and you'll about average out to mid grade.
 

Prime

Shut up Baby, I know it!
Admin
Location
Denver Adjacent
I also have a Pathfinder with the tow package same VQ40DE engine and it states on the fuel door "Premium fuel is recommended for maximum performance for best performance". I can't attest that the tuning might be different but same engine and runs on all fuel types but tows better with premium fuel for sure.
My ex wife had a 12 Pathy with the same sticker on it. I ran premium in it for a while. Didn't notice a difference going to regular.

Here in CO, our base octane is 85 (because less air density at elevation means you can run lower octane and not have detonation) and I can't tell a difference between 85 and 92 here.

I can however tell a difference when I stop at a station that has ethonol free gas. Engine is so much happier.
 

Prime

Shut up Baby, I know it!
Admin
Location
Denver Adjacent
The whole point of increasing octane is to reduce the possibility of detonation. Which can ufck your engine up. That's why high performance vehicles require premium. Higher compression, forced air induction, aggressive tunes. These things can all contribute to detonation with lower octane levels.
 

MisterH

Bought an X
Location
Washington State
Well, I have 2 Xterras, and with the gas prices, they're lucky to get gas:D I do about 70 to 90 miles a day. My first Gen is peppy with higher octane gas, but not enough for the cost. It already has an oil habit. I had a 91' Ford Probe with 4 cylinder demanded 91 octane
 
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