Old mechanics trick, for rounded bolts (and wheel locks) you can normally find a standard or metric 12 point socket to pound onto the bolt. The above hammer and chisel method does work too. Seriously. But make sure you have a replacement on hand and be careful.

When removing oil plugs you always want to use a 6 point socket or the closed portion of a wrench. Make sure everything is square and if you can swift application of torque is desireable. Never use the open end for anything aside from removing an already loosened bolt if you can help it.

 

If it were me, I definitely would not use an impact. Try hard to get a 6-point socket on the plug and work to not round it. Once rounded, take the advice in the posts above.

 

actually was a 6 point slid the hell off of it.

figured it's cause it doesn't have muchto grip to added to the fact it seized.

Whenever the bolt remover ships I'll give it a spray and get it out...

 

Try welding a nut to the drain plug then remove it like normal

 

Isn't the plug aluminum? This might be difficult for the average joe.

 

Impacts are great for REMOVING bolts. Due to the nature of their design, I've found over the years that you are LESS likely to strip/round bolts REMOVING them with an impact and a good six point socket. HOWEVER, you can't always get one where you need it. PB blaster, or equivalent in the OP's case is then your next best option. I've found that if you are in a predicament where it's quickly obvious that a wrench alone is not going to do it. It's better to hit it with a penetrant, and let it sit for a day. Then tap it with a hammer before twisting on it. The hammer is just a "shock" treatment to help loosen things up. Between that, and a days soak in penetrant, things go pretty well.

BTW, I don't own many 12 pt sockets/wrenches, and won't for a reason, if a bolt won't budge with a six... best to start the process above.