Feather it if it's still servicable. If it's 100% killed (dead, not spinning) you can't do anything.
Technically it's not "feathering", as the blades don't turn completely forward, unless you fly certain planes that feature this, like the P38. You're really just reducing RPM so that there's less of an air brake on the front of your plane.
If you've still got a servicable engine but are losing oil, climb for home at full WEP. You have an oil gauge in your cockpit. When it gets down to below 50, kill the engine, reduce RPM and glide. You might need that last bit of oil to land (if you have to manuver around some trees or are coming in just a hair too slow).
10k alt and moderate speed should get you 30mi or more safely with engine off. 15k you can glide for almost 1.5 sectors or more. That's why I say climb at full WEP. Engine temp and gas mean little when your oil will run out before either. If you're already at alt, level out and WEP for home (just to get there faster, and if you have to kill the engine you can climb or coast on the speed you have).
All probably obvious, but I thought I'd spell out a few things I do.