Hi,

2003 V70 2.5 AWD with 107K miles. I have always run this car on premium gasoline as the owner's manual recommends 91 octane.

I realize I can probably run regular 87 octane and the engine computer will dial back the ignition advance - resulting in lower power and reduced mpg. However, other than that, am I doing any other damage to the engine?

Thanks

Bob

 

I don't think so. The engine only has a compression ratio of 9:1 or thereabouts. The turbo is relatively low pressure. I really don't think it requires premium, I don't use it, and I get the EPA MPG numbers or slightly better.

I think premium is really only important once you get to compression ratios of 10-11:1 or larger turbos.

 

Well if the volvo engineers did their job, theoretically no. If the ECM and knock sensors are working properly, it should not.

But this topic has been discussed on this and other forums ad-nauseam and everyone seems to have an opinion about it. Some claim it causes the valves to burn/pit pre-maturely but how the heck are you going to prove that unless you do long term double-blind testing, etc.

Considering the price delta between regular and mid-grade (92 octane) here is about 3%, I opt for the mid-grade myself, and appreciate the extra performance and mileage.