[Destructo09]

It'll be fine, I wouldn't even bother siphoning it out. After you run the tank out and refill with 91/93 then do the fuse pull.

My motorcycle makes 150HP on a 1.0L engine, like somebody else said it runs on 87 octane. However the other person didn't bother to bring up dynamic compression, this is what truly makes the difference on fuel octane. The cams in my 150HP 1.0L engine have so much overlap that it must idle at over 1k rpm and this causes the dynamic compression to be low enough that 87 octane is just fine.

Bottom line, 87 octane won't hurt a stock non-tuned LS3, if it could then lots of folks with brand new SS Camaros would be in trouble lol. The owners manual even states that regular fuel is ok, but 93 is recommended.