[masraum]

Originally Posted by flipper35

I broke three of those trying to get a bolt out of an intake manifold. With lots of penetrating oil overnight. Left hand bit did the job, mostly.

I've never had good luck with those. I wonder about them because as the thing bites and "screws in" to the hole that you just drilled, it also expands what's stuck into the hole that it's stuck in, which seems counter productive.