Hello All,

I purchased a gently used 2016 XC90 T8 T8 Plug-In Hybrid Inscription with 12,000 miles on it last December. According to the owner’s manual that came with the car (it is a summary of the full manual), on p. 101 it stated “Volvo recommends premium fuel for best performance but using 87 octane or above will not affect engine reliability.” Under this in a box there was information that stated:

“Minimun Octane Rating (R+M)/2 Method 87”

At the bottom of this same page the manual identified two high performance 4 cylinder engines (B4204T9 and B4204T10) that require premium fuel. My T8 is not equipped with either engine (It has a B420T28).

Subsequently, I obtained a copy of the complete owner’s manual (544 pages). On p. 362 it stated: “Volvo requires premium fuel (91 octane or above) for best performance.” Underneath this paragraph was a box that stated:

“Minimum Octane Rating (R+M)/2 Method 91”

Both the summary manual that came with the car and the complete manual I subsequently obtained were published in 2015. Puzzled, I called Volvo Customer Care. The representative said I should be guided by the information in the complete manual and disregard the information in the owner’s manual that came with the car that recommended minimum octane rating of 87. I put a call into the service desk of my local Volvo dealer and the service writer said I should follow the instructions in the full manual (disregard the 87 octane recommendation in the manual that came wit the car) and use 91 octane. He said it was required because my Volvo was equipped with a supercharger and a turbocharger.

I have driven the car using 87 octane and have not observed any adverse effects over the past 12 months. There is no 91 octane in my area. The grades go from 87 to 89 and then 93. There is on average a difference in price between 87 octane and 93 octane of approximately 50 cents per gallon.

I remember back in 1996 when I purchased my first Volvo, a non-turbo 850 GLT Wagon, the owner’s manual recommended an octane rating of AKI 91 or above, but at a minimum octane rating of AKI 87. AKI stands for “Anti Knock Index” which is an average of the Research Octane Number, RON, and the Motor Octane Number, MON. (RON + MON/2).

At a Volvo Open House in Rockleigh, NJ that I attended, a Volvo engineer said I could safely used an 87 octane gasoline and would not damage the engine in my Volvo. I followed his advice and did not experience any “knocking or pinging” with my two 1996 850 wagons.

Fast forward to today. I would like to use 87 octane gasoline instead of incurring the additional expense of 91 octane. However, I received contradicting informations in two Volvo owner’s manuals. The Volvo representatives, and this is no criticism, basically read back to me the contents of the full Volvo’s owner’s manual.

As I said, I would like to use the 87 octane gasoline, but will not if I run the risk of damaging the engine in the long term. I would welcome any comments or suggestions. Thanks in advance to all who respond.

Hugh