i advise against it.what happens with a higher ratio engine is using lower grades in cars like your gfs tsx will cause knocking. immediate effects are: notable degrading performance,worse gas mileage.while back in the day knocking would kill an engine, modern technology made it that it doesnt happen immediately, but keep doing it long term and you might just pay for it (engine wise).i cry a little inside when i see bmws,lexus,acruas at gas stations putting 87 or 89 in their tanks (which is why i will never own either used).
