A friend that is a Subaru tech showed me this gizmo a couple of years ago, so I finally splurged on one this week:
http://www.amazon.com/dp/B00A6AS6LY/?tag=ihco-20
It works exactly as promised/designed. You find the proper adapter and cap fitting for your radiator, insert the big funnel, and start pouring in coolant. When it stops, leave the funnel about half full and start the engine and let it warm up with your heat on high. Eventually when the thermostat opens, all the air in the system will work itself out, and the fluid in the funnel will top it off. When the bubbles stop coming out, you stick the plunger in the bottom of the funnel, lift it off, drop it into the reservoir and pull the plunger back out. I did my system the other day and didn't spill a single drop. No big puddle of pet-unfriendly coolant on the garage floor to clean up.
http://www.amazon.com/dp/B00A6AS6LY/?tag=ihco-20

It works exactly as promised/designed. You find the proper adapter and cap fitting for your radiator, insert the big funnel, and start pouring in coolant. When it stops, leave the funnel about half full and start the engine and let it warm up with your heat on high. Eventually when the thermostat opens, all the air in the system will work itself out, and the fluid in the funnel will top it off. When the bubbles stop coming out, you stick the plunger in the bottom of the funnel, lift it off, drop it into the reservoir and pull the plunger back out. I did my system the other day and didn't spill a single drop. No big puddle of pet-unfriendly coolant on the garage floor to clean up.