What is the better gas option for a 2007 Scion tC?

Question

The manual for my 07 tC says to use 87 octane gas. Here in New Mexico, our "Regular" gas is 86 octane, and our mid-grade is 89. I've read that using lower octane isn't good, but then ive also seen that the 89 wouldnt be good either. Which would be the best option?

Answer 1

You would probably be ok with the 86, but if you have performance issues or pinging issues, I would recommend mixing the 89 and the 86.  

Put 89 in, and then refill with 86 when you get a half-tank.

Let it go to about 1/4 tank and then repeat.  

It works and will be the best option for your pocketbook and piece of mind.  

Answer 2

Octain ratings are just that.  They are a bottom line for gas companies to comply as a regulation.  The 86 or 87 only states that if tested that is the minimum that the rating can be for that gas.  Most likely it will test 88-90 most of the time anyways...

Answer 3

The car will run fine on regular, but stay consistent!  The engine fuel control has a 'Learn' system and does not like changes in fuel.  It takes many miles to learn a new octane level in the fuel.  

Stay with the recommended value, and use any fuel with a carbon cleaning additive (techron, shell etc.)

good luck

Answer 4

you are at high altitude ? Use 86.  

In the Rocky Mountain (high altitude) states, 85 octane is the minimum octane and 91 is the maximum octane available in fuel. The reason for this is that in higher-altitude areas, a typical combustion engine draws in less air per cycle due to the reduced density of the atmosphere

It is safe to fill up a car  that normally takes 87 AKI fuel at sea level with 85 AKI fuel in the mountains,