Here again, we ALL want to save money where we can, but this may not be the place either. We've all heard "You get what you pay for" OR... "Put cheap in, get cheap out" This is so true with fuel too. Most of our Subies are 4 cylinders, that are hauling a reasonable sized car around. Not to mention all the Kidz, Kritters, Koolers, & Kayaks we tend to take with us. So when their manual says "87 MINIMUM" take it seriously. If for no other reason, consider this... Cheap fuel could cost you not only fewer MPGs but a possible $800.00 to $1200.00 catalytic converter later in the cars life. You want better gas mileage?? Use good gas & check your tire pressure. Of course we've all heard this, but only one or two cars out of ten that come into our shop have the proper air pressure in their tires.