jeverett72

I have a 2013 GS 350 AWD. I know that Lexus states that 91 octane is the minimum recommended octane for the V6 engine. In my area of TX there is premium (93 octane) which is mixed with ethanol or completely ethanol free (90 octane) gas available. Which do you think is better for performance, gas mileage and the engine in general?

Dreamcast

There's a detailed article from a tuner that said to always use premium fuel. Make of that what you will.

Hues10

Here we go. Should we use or not use Premium Fuel? Should we or should we not change the transmission fluid? The never ending questions where people argue endlessly and there is never a definite answer. I do use 93 Octane from Costco in my 2013 GSH. But I do admit, on a trip when stopping for gas in April, the difference between 87 and 91 octane was something like $.90 per gallon. No freaking way I was paying that. I think I had half a tank anyway of 93 so I mixed it in. Figured I would run through most of the mixture the rest of the way home, and fill up again with the 93 Costco. Did my engine start coughing and sputtering, of course not. Has anyone consistently been putting 87 octane in, driven over 100k miles and reported any problems yet? I know, you own a Lexus, pay the price. I say to each his/her own. Do what you want. It is your vehicle. My two cents.

GSJ350

When all vehicles are designed engineers must take into account varying qualities of fuel from country to country and state to state etc... The truth of the matter is it might say it's 93 but if you tested it, it could be 90 or maybe even less. The vehicles ignition timing will be retarded for lower octane and advanced for higher octane, so if ultimate performance is what your after always run the highest octane you can. Ambient temperature should also play a large roll in your selection as well since hot air is less dense it's prone to pre-ignition (Detonation...pinging...marbles in your intake mani&#128556 so higher octane is required in hotter climates in most cases unless you have a low compression engine which wouldn't need 93 and could probably get away with 89 or so. The opposite is true in cold weather in which the air is more dense which allows it to be compressed without the fear of pre-ignition on lower octane fuel. The last thing I'll say is that if you can run low (87) octane without pre-ignition occuring, higher octane won't benefit you.

NJLEXES

If you want to see an excellent video explaining everything you could want to know about gas and then some, here it is....