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Re: Fuel Grade?[V70/1998] posted by abe crombie on
Sunday, 3 May 1998, at 11:15 p.m.
All Volvo gas engines since 1986 have had knock sensor function in ignition that will adjust to lower octane fuels. This adjustment comes at the expense of lower performance and lower MPG for most persons. The sensitivity to lower octane is greater for turbo engines. There is also a lowered level of fuel imjector/valve cleaning detergents in the lowest octane fuels of many suppliers.
I can tell the difference between 87 and 89 octane in any weather and I seem to be able to detect a difference between 89 and 92 in hot weather or when heavily loaded on late model 850 non-turbo cars that I've driven. If you drive aggressively then 92/93 is a good idea. If you drive long distances on highway lightly loaded then the 89 octane is probably your best value. I wouldn't use 87 as it would likely result in more fuel usage and more internal engine deposits in the long run.