3.0 Boxer Octane Requirements

I have a 2005 Outback Sedan with a 3.0 Liter DOHC Boxer Engine. The specs say the compression is 10.7:1. The owners manual suggests 91 Octane as a minimum. Will running 87 or 89 Octane hurt anything? Looking to save a few dollars....

Why does everyone want to do this?? You risk hurting your engine and your gas mileage so you can save like $2 every time you fill up. I run the highest octane I can find. When you spend good money on an engine, take care of it. Or buy a KIA. Seriously, if you are going to try this, do it slowly. Fill it up with 89 when your tank is still half full. In the next tank use 89 take it down to half then fill with 87 and so forth. You don't want to "shock" the engine with 87 when you have been running 93. The computer has to make adjustments over time to the lower octane (or so I have been told)

IIRC, the earlier boxer motors required 91 octane but the later ones could take lower. I think I just read that in the last issue of Drive Magazine from Subaru. Either that or the one before it.