What octane of gas do you use in your Prime ?

The the US and Canada, we use a weird Octane rating called AKI. Most of the world uses Research Octane Numbers (RON) but some of the world uses Motor Octane Numbers (MON)

Just to make life challenging, the US, Brazil, and Canada use AKI which is (RON + MON) / 2 or the average of RON and MON. I bet some government bureaucrat got a raise for that.

Octane rating - Wikipedia

87 is fine. But in general, use what is recommended in the owner's manual, any where in the world. Toyota's recommendations will change with local conditions. (Especially lubricants)

 

As often as I put gas in mine I've been using Premium.
Probably costs me $5/yr more to do that.
I figure the car will repay me some day.

 

North American Owner's Manual gas specifications are always confounding. I gave up trying to make sense of it about 40 years back. It makes my head spin; @JimboPalmer seems to have nailed it though.

All I cling to: every car we've ever had, and most every car on the road, is fine with regular. And with computerized ignition timing and fuel injection, even the cars that do specify mid or high octane gas can adjust (if needed), if regular is used.

Which begs the question, and I really don't want top open that can of worms (or do I...): why do all the octanes get equal billing at gas stations?

https://www.cbc.ca/marketplace/m_episodes/2012-2013/pump-fiction

 

Because some parts of the world use a different "system" to measure exactly the same thing......and come up with different numbers.

And yes, it is perfectly fine to use whatever is considered "regular" wherever you live.
Premium is just a waste of money.

 

You figure wrong.
Higher octane than you need can sometimes result in less power and a higher rate of carbon accumulation.
In addition, if you buy that high octane gas from a station that doesn't sell a lot of it.......you may be getting gas that already is a LOT older than you might think.

But if it somehow makes you feel better...............

 

Probably not valid any more but at one time Premium had more/better additives which are a separate thing from octane.
Also my cousin who worked for Amoco said said they dispose of reclaimed fuel by adding to to the storage tanks of Regular grade gasoline. Probably measured in parts per million but that tidbit stuck in my brain.

 

It does. I go to stations that draw Lexus(es) as they should burn premium according to the owners manual.
By the time the gas is actually burnt in my car is will be another six months old on top of the week or ten it spent in the distribution network.

 

Regular is high volume, economy of scale
Premium is high profit margin, charge idiots all they will stand.
There is no middle octane tank, they just mix them in the middle pump.

 

The US EPA required detergents in all gas in 1995. Some auto makers thought he standard was too low and started the idea of Top Tier Gas in 2004.

If you use Top Tier gas all grades have the same detergents, the gas station has to use weasel words like "No Gasoline offers better cleaning" as they are all the same.

All non top tier gas has to meet the EPA standard.

Top Tier Detergent Gasoline - Wikipedia

I have no idea about other countries.

 

Regular unleaded octane rating (87) is all it needs. I have never tried using anything else on my PRIME, yet my lawnmower gets high octane (91) premium gas.

 

The reason I use Premium gas for our lawnmower is not so much about octane rating, but in our local, the ethanol-free gas is only available in the Premium grade. And, in addition I even use gas stabilizer with it for all of my small engine power tools.

 

I had understood that this varies. Some stations mix their own at the pump, some have it delivered to a separate storage tank.

A bit of searching found the storage tank filler cap color codes. So if asking about any particular station, look at the colors of the underground tank caps:



There are some other charts available with even more color codes.

 

I use 85 octane exclusively in Colorado. Thats what they sell as regular. The higher altitude means there's less oxygen available to the engine (about 15% less at 5,000 feet), so less horsepower is reduced, and lower octane can be used. That applies to naturally aspirated engines. Turbocharged engines might be able to compensate for the lower air pressure and probably need to stick with what the owners manual recommends.

I've never had a problem using 85 octane here, but I have had problems using it at lower elevations. One time I filled up my Honda Civic with 85.5 in South Dakota, assuming that if it was for sale it must be just slightly lower elevation than Colorado. But it was actually around 1,000 feet, and as a result the car was severely lacking in power and got around 22 mpg on the highway for that tank.