I see in the FAQ that
Are the ill effects of using regular gas for 60,000 miles at all reversible if I start using premium now? By other means?

Suppose you had the power to know for sure, would you be detered from buying a max that ran on said gas for that many miles?

 

Running lower octane gas in a big bore vehicle or high compression vehicle can cause damage to the pistons and rings. Just switch to premium you'll also get better mileage using premium. There's not really a good excuse to not run premium in a vehicle that requires or recommends it.

 

and you don't really save all that much running a lower grade. If you filled up your tank using 89 instead of 91 or 93 you save like 1.80. Not worth it

 

Most of that savings is negated by poor fuel consumption

Also if there has already been damage there is no way to reverse it, but running crap gas can cause oil consumption to rise dramatically.

 

Guys, I realize the benefits and I'm using premium.

The reason I asked is because I'm the second owner and I know for a fact the previous owner never used premium. So I was wondering if the damage (if any) can be undone.

 

Assuming there has been damage then no, you'd have to tear the motor down. But dude a lot of folks that buy them dont ever run them hard if it hasn't been run hard you're probably fine.

 

This is the reason we have knock sensors.

 

my little 2.0l s2k requires premium -- oh wheres does my $ go

 

Yeah, i did the math one day when my mom and gf both yelled at me, "you waste money on putting that stuff in your car?!" even with filling up at half a tank, i took the highest price of gas stations around here and the difference was like $2.53 more for 93 octane. I'd just try to get the engine in better condition, your already using premium, run a can of good injector cleaner, run some Auto-Rx, seafoam through the mani, and switch to synthetic then change the plugs.

 

It's a big bore motor thats part of the reason and the compression is pretty high....but what an oh so wonderful car to drive...I LOVE the S2k. Quick and VERY light on its feet.

 

Is the use of Regular gas has anything to do with EVAP Control System going bad??

 

code 440 or 442?

 

I wouldn't worry about it at all. No need to tear the motor down or do anything at all. The car has a knock sensor which will retard the timing and prevent detonation. It doesn't damage anything at all.

Premium gas actually does improve performance if the car can take advantage of it. Retarding the timing on any vehicle cuts power and efficiency. The previous owner never saw the full power potential of the car but they didn't hurt anything.

Put the best gas in it from now on to get the best performance from it. I wouldn't worry about anything else.

If we were talking about an ultra high performance car I would have a different opinion. Those cars are built to make the most power they can. Durability isn't as important and the owners are expected to know how to take care of them.

Regular passenger cars are designed to be idiot proof. Nissan knows people will put cheap gas in them and still expect them to last for ever. I wouldn't worry one bit.

 

My friends dad has a 97 infiniti Q45, he bought it in 98, he put about 70,000 miles on it since then. He always puts 87 in it (infiniti says 93)and it still runs perfect, very quiet and powerful

 

I was curious about this myself so I did a little research. I ran two tanks of 89 through the max and my avg. mpg was 19.6. There was also a noticable difference in the engines response. After running two tanks of 93 the average MPG shot up to 23.2 (same driving conditions, same avg. temp) and the response was vastly different. In the summer when it becomes more available I had wanted to try running a few tanks of 99 to see how that would wake her up. But with 93 @ 2.57 a gallon it may be a while before I do that