I regularly get gas from Costco and I recently moved to Colorado.

The Octane rating at the local Costco here is 85 or 91 Octane.

Was wondering if I should be concerned about engine knocking even though Hybrid engines aren't always running.

 

Per the manual choose Octane Rating 87 (Research Octane Number 91) or higher.

 

I've been using 85 in mine for 1.5 years now.

Mine is super white as well.

 

Octane requirements are less at higher elevations, such as in Colorado, which is why lower octane gasoline is sold. Nothing to worry about.

 

Are you in the mountains? At high elevations, the octane requirement of the gas engine goes down (as does the power). So, at altitude, 85 octane should be OK. If you drive to 'the flatlands', you may get less power and a notice a bit of spark knock, as the higher air pressure increases the octane requirements. Most cars don't have enough range for that to be an issue...

 

The 85 Octane matches the 50% less oxygen at this elevation. I have tried 87 and 91 and found no mpg improvement at all. I have not seen any engine knock with the 85.

We have had our TCH for a year now.

Bill
Denver.