I know I've posted about the gains with a 100+ octane gas (which I understand is minimal), but would it have any harmful effects to the engine, as long as I completely empty out my tank of old gas first?

 

no, higher octane is meant for cars with high compression. you wouldn't really be doing anything

 

http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm

oh wait.. that's for those people asking about if higher octane better... blah. blah...

uhh... i don't know how harmful it is to run at such a high octane, but i have heard there is a point where an engine can burn gas too cleanly.

i just wouldn't do it.. nor waste the money... but hey... your choice.

 

I bet your O2 sensor will love the leaded gas. Unless you're one of the lucky people that can get Unleaded 100oct at the pump

But really it's just a waste of money.

 

I meant unleaded. I'll actually try it today and see how the 100-o unleaded is. Not expecting too much though.

 

higher octane gas burns slower and will probably lower your mpg a little from the reduction of peak pressure at spark ignition due to the slower burn. it is only needed to prevent knocking in high compression engines and may cause slightly elevated exhost valve temps which you will never see anyway.