85 octane?

[Tanners Owner]

Recently moved to Idaho where they sell 85 octane fuel as “regular”. I’ve been buying 87 which is mid grade here.

Also saw in the manual Jeep states to use 87.
“This engine is designed to meet all emissions regulations and provide excellent fuel economy and performance when using high-quality
unleaded “Regular” gasoline having an octane rating of 87 as specified by the (R+M)/2 method. The use of higher octane “Premium” gasoline will not provide any benefit over “Regular” gasoline in these engines.”

My Q is there any real risk in using 85 octane?

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[fourfa]

Not while you remain up at the altitudes where they sell 85 as regular. Less air pressure = less mass of air in the cylinders = less peak cylinder pressure = less octane needed to resist detonation at lower peak pressure.

(might be different with a turbocharged engine but do note this is in the pentastar sub)

Biggest risk is you drive down to low elevation on 85 and decide to do street drags or mud pulls. Just take it easy until you fill up on 87.

 

[v0mitus]

I would only use 87 or above. As you said the manual says to use 87. And If anything goes wrong and warranty work needs to be performed I would imagine FCA would take exception.

 

[JW Jeep]

I’ve been running 85 octane since new and never had a problem over 10,000 miles. It’s the altitude here in Colorado also. You also will probably get better MPG ? I get around 23 around town and as much as 26 on the interstate long as I say under 75 MPH.

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