What grade of gasoline should be used for the Volvo S90?
2 Answers
The Volvo S90 should use 95-octane gasoline. This gasoline grade is recommended in the official vehicle manual for this car. In addition to checking the appropriate gasoline grade in the vehicle manual, you can also find it on the fuel tank cap, which will also be marked. Typically, the gasoline grade can also be determined based on the engine's compression ratio. Cars with an engine compression ratio between 8.6-9.9 should use 92-octane gasoline, while those with a compression ratio between 10.0-11.5 should use 95-octane gasoline. If the compression ratio is higher, 98-octane gasoline should be chosen. However, with the use of some new technologies nowadays, the gasoline grade cannot be solely determined by the compression ratio. A high compression ratio can also be tuned to use lower-octane gasoline. This is because, besides the compression ratio, other factors such as ignition timing, turbocharging technology, and Atkinson cycle technology also play a role. Generally, the higher the gasoline grade, the higher the octane number and the better the anti-knock performance. 92-octane gasoline contains 92% isooctane and 8% n-heptane, while 95-octane gasoline contains 95% isooctane and 5% n-heptane. If the Volvo S90 occasionally uses the wrong gasoline grade, simply switch back to the correct grade after consumption. However, prolonged use of the wrong gasoline grade can have the following effects: For vehicles recommended to use lower-octane gasoline, accidentally using higher-octane gasoline will not cause damage, but the increase in octane number will change the fuel's ignition point, leading to delayed combustion in the engine. This means both the engine's power output and thermal efficiency will decrease, resulting in poorer performance as experienced by the driver. For vehicles recommended to use higher-octane gasoline, using lower-octane gasoline can cause engine knocking. Because the octane number is too low, the gasoline's ignition point decreases, causing it to ignite prematurely during the compression stroke. If combustion occurs before the spark plug fires during the compression stroke, resistance will arise in the upward stroke. This resistance makes the engine run very unstably. If the knocking is imperceptible, it only increases noise and does not significantly damage the engine. However, if noticeable knocking occurs, it indicates severe engine conditions. The vibration not only affects driving stability but also causes abnormal wear on the pistons and cylinders, and in severe cases, can lead to cylinder scoring.
Over the years of driving my Volvo S90, I've consistently used 95-octane gasoline as clearly recommended by the manufacturer in the manual. My 2019 turbocharged model runs smoother with 95-octane fuel, minimizing annoying issues like knocking or abnormal noises. Higher-octane fuel offers multiple benefits: more complete combustion, surprisingly better fuel efficiency, and stable power output during long highway drives while saving money. Once when I accidentally filled up with 92-octane, the car felt sluggish with delayed response, so I promptly used additives to compensate. I always choose branded gas stations over cheaper independent ones for quality assurance. Also, when refueling, never exceed the tank's maximum capacity - leave some space to prevent fuel spillage that could damage paintwork. Following the manual's fueling recommendations helps avoid major engine repairs, protecting both your investment and convenience.
