What size tool to remove the plug on the driver side of the block to drain out the coolant?

I tried a 3/8" and 1/4" ratchet without a socket, the plug has a square hole, and the 3/8" drive is too big and the 1/4" drive is too small.

Any info on this would be great.

 

Maybe 5/16" bar stock available at the hardware store?

 

I thought about that, but shouldn't it be a certain size for tool use?

 

Good ? for Jeep/Chrysler.

 

item 94961 at Harbor Freight was on sale for 13.99 for the set plus i had a 20% off coupon. Found these by accident when I was looking for something else. These sockets also have a life time warranty. comes in metric and standard sizes. By the way it is the 5/16 that you need for the plug.

 

Yea there are tools for it, My machinist shedded light on it. Its an odd size but its 5/16"