I have noticed premium only sign only after filling with plus 89 fuel. Anything bad? On my old honda, putting lower grade introduced some pinging noise on uphill exploding during compression. Didn't notice on my TL.

 

 

Our TLs are designed for Premium gasoline, I believe 91 and up if I am not mistaken. I only recommend what the manual says. It's your car do as you please, but putting 89 in a TL is going to bring about problems. You might wanna try searching as well, I think there are a couple of threads on gas.

 

The knock sensor will detect the pinging, retard the timing, and you will be fine. The only thing that will suffer is performance and mileage on this tankful.

 

you'll be fine, but your engines performance will decrease slightly. You may not notice it unless you are in tune with your car like it's an extension of your body. Most of us here are and would feel a difference. I can feel a difference from 91 to 93 in my car.

 

what they all said. dont think you should notice it if you're not a particularly aggressive driver.

 

You will be fine. The ECU will adjust for it properly. When its time to fill up put the 91+ in it.

 

I do find that hard to believe since the car was tuned for 91, and higher octane wont improve any thing. 87 to 91 yes, i can tell the difference.

 

I definitely feel a difference. My car has 161k on it so they is bound to be carbon building in the cylinders that even seafoam cannot get rid of so higher octane would be beneficial in this case as the cylinders would have a higher compression ratio because of the carbin buildup. Correct me if I am wrong, but I believe this is what I've read on numerous ocassions.

 

There shouldnt be any carbon buildup enough to feel the difference in octane that close. Especially seeing how clean the inside of my motor was at 200k. there was VERY little at all.

 

that's great to hear and hopefully that's the same with my car, but I still can feel a difference. Just like after running a good fuel system cleaner or seafoam. I have even used a few octane boosters and while some do nothing I found NX Express worked well and there was a difference in throttle response and top end pull.