XC 90 Fuel Question

[iceb52!]

I just bought a 2005 XC90, 2.5T, Front Wheel Drive. Owners manual recommends 91 octane for the fuel. It also says minimum octane is 87.

Local gas stations carry 87, 89, and 93 octane. With fuel prices continuing to rise, I prefer to run the lower octane fuel. However, I do not want to harm the engine running less than 91. I am interested to know what problems may arise running either 87 or 89 octane. Performance is not that critical for me, but I do not want to tear anything up either.

Any comments will be appreciated.

[matthew1]

Sub 91-octane fuel will not hurt your engine, because your engine's computer will retard the timing to prevent ping/detonation, which will have the effect of lowering performance/fuel economy a tiny bit. You may be able to see this statistically if you take careful recordings of mpg for perhaps 10 tankfuls of each: 91 and 87 octane.

[Guest]

It's not that critical to run 91 Octane, you won't see short or long term problems with your engine. Engines and fuel management systems are very well designed and have very high failure thresholds.

Maintaining the proper oil level and oil changes themselves are more critical, especially with Turbo's. Change your engine oil per the OEM specification. I've worked on piston driven airplane engines nearly 40 years old that continue to run; because engine oil is changed by hours rather than miles...

[rob]

I have rarely used 91 in my T6. 37,000 miles later, I haven't had a single problem. Fully loaded, empty, plains, mountains, all weather, Thule on top.... I do believe I can detect slight - barely perceptible (or is it my imagination?) - performance gains with the higher octane. My recommendation - save the $$$$.

[xc90incanada]

I use 87 octane and feel no significant depreciation in performance. I used to have a 1.8T VW and it has drastic performance drop if not using at least 89. No such on the XC90.

Any opinions out there on the various blends of fuel like 90-octane Ethanol blends.