Octane vs mileage

My 2006 Lexus ES330 book says I can use High test mid grade or low grade gas. Does the high test give me better mileage?

If it does is the increased mileage enough to offsett the cost diference.

Jack Machun

San Rafael CA

Don’t double post the same question.
You’ll need to test for yourself because of computers these days. my old 92 Explorer gets NOTICEABLY better mpg using 91 octane vs 86, yet my 06 Escape hybrid has never shown any better with premium.

Here’s a link to a thread I started on this issue. The short version is that there was no change in mpg betweem premium and regular gas in my wife’s 2006 Sienna.


Ed B.

In general in a car that “recommends” high octane, then high octane will result if better mileage. If it says it needs high octane, then it may or may not increase the mileage a little, but using regular could cause damage to your engine.

Usually the mileage difference is not great, but it does vary from one car to another as well as the conditions (altitude temperature speed etc.  In both cases using regular will likely reduce power as well.  

If the owner's manual recommends regular, then it is not likely that using premium will increase mileage or do anything else positive for you.  In a few cases it could damage the engine.