I have a 2025 ES-350 UL and normally run regular (87 octane) fuel as recommended by the manual. Would occasionally running premium (91-94 octane) fuel cause any issues? I doubt that it would cause any problems but thought I'd pose the question anyway.

 

no issues at all
my 2016 GS 350 requires premium pretty much the same engine.

 

No issues, octane rating is just a measure of fuel quality (higher detergents, better combustion). I run 2 tanks of 91 on my 2025 ES300h every 5,000 miles to clean my engine from potential carbon deposits that accumulate in direct injection systems.

Even on cars that require 91, running 87 on them will be fine, it will just lose a little bit of performance.

 

Just the hit to your wallet.

 

Running "Top Tier" fuel should take care of getting fuel with higher detergents across the octane spectrum.

 

Actually octane rating is a measure of the fuels ability to resist knock as compression increases. The comparison is to Octane gas/liquid when used as a fuel.

 

Done this since day 1 on our 2015 ES and regular octane has caused zero issues with the car. Costco sells top tier rated fuel and its usually the cheapest in our area.

 

No, it's not.
Read the post number 6.

 

No issues using higher octane fuel but just a waste of your money...

 

It think this mandates a famous gif.

 

Using “Top Tier” gas (as recommended by most automotive companies including Toyota/Lexus) is what will keep your engine clean and carbon buildup free. You can find the places that sell Top Tier gasoline online, many companies do, but some like Sam’s, Pride and Cumberland Farms do not (Costco does).

https://www.toptiergas.com

 

I run Top-Tier Costco 87 octane in my '23 ES300h, and annually or every 6 months I use a bottle of "Techron Complete Fuel System Cleaner" purchased at BOGO for around $5. This achieves the same premise in a more efficient and cost‑effective way.

If you're not using Top-Tier fuel, I recommend using "Techron Complete Fuel System Cleaner" when it’s available on BOGO (which is fairly frequent) and running a bottle once a year or every 6 months. This approach is more efficient and cost‑effective than using a few tanks of premium fuel. Even the owner's manual recommends adding an "EFI fuel tank additive" every 5K/6M in certain regions, which is essentially the Toyota brand of Techron.

 

Historical note: Premium (High Test, Ethyl) higher octane fuel used to have the cleaning additives that Regular did not. Filling a tank with Premium would have some of the benefits we are attributing to the use of additive products mentioned here.

 

Has anyone tried TopTier+ fuel? Top Tier has a new higher grade of gasoline. I have yet to find it anywhere though.

https://www.toptiergas.com/top-tier-plus/

 

i do all the time, Shell, Citgo, Mobile and Phillips 66 sell it here in Ct, others stations do also. I assume those brands sell the + across the US. It is easy on the website you posted to find stations in your area. The have a “station finder” on the web page.