Like everyone has been saying: there isn't really any difference between premium and regular. With that said, I don't think it would harm your car at all if you switched back to regular.

 

no it won't.

First of all, initially when you filled up with premium its almost certain some 'regular' was still in the tank, so this diluted the premium a little bit, so for the first tank it wasn't pure.

It's not a modded car, so switching between fuels won't do anything.

 

My 2000 has 123K on the clock, I use regular E10 and get 26-28mpg combined - more highway miles than city [65 mile commute each workday]. Have been able to stretch the tank to 450 miles but not much left... maybe 1/2 gallon.

 

My personal best on my 93 is 385 miles on a tank. That was pure highway running 80 - 85 MPH the entire time. When I am driving city/highway mix, I usually average about 330 miles per tank. I have been using 87 octane.

 

Of late, last couple weeks, I'm smelling some pretty heavy gas vapors coming from my 97 es300. Any of the usual suspects I can start looking at?
Cheers,
DD

 

running rich at start? or at all times?

 

I can drive 5 miles or 50 and shut it off outdoors and when I open the door you immediately smell the fumes.


DD

 

Did it rev longer time to start? Try to clean the MAF sensor.

https://www.clublexus.com/forums/es3...af-sensor.html

 

Thanks for the information on this sensor. I just scanned though the FSM before reading your reply and don't recall seeing anything about it in there.

I'll pull it out tomorrow when my wife gets back and let ya know.

DD

 

I was surprised when I took the MAF out to clean it. I shot it 3-4 times with CRC and no buidup run out, actually it looked pretty clean. But now I'm getting a long 3-4 second start.

I'm starting to think it's a gas tank leak as the smell does seem heavier from that end.

No joy,
-DD

 

Try to clean or replace the PCV valve too.
After cleaning this 2, reduce my 90% smoke from first 5 mins.

https://www.clublexus.com/forums/es3...pcv-valve.html

 

I have a 1997 Lexus ES300. As long as I have had it, I have been using 87 octane fuel. I want to experiment and possibly try 91 or 93. would this mess anything up? and can i put 91/93 in the tank if there is left-over 87 in the tank?
Thanks in advance for your help.

 

Mixing the fuels won't hurt anything. If you are very sensitive to your car you might notice a little more power and, if it's been pinging at all, that should go away. Otherwise, you might notice just a little less fuel mileage but I don't think it's enough to notice unless you keep very close watch on it.

 

Just wondering what octane gas do you put in your ES or Lexus??

 

I always used 89.