It uses a T45 Torx bit.
14mm
You will need a Torx style bit or wrench to fit into the plug (size T40). A small pipe wrench which grips the outer flange of the plug can also be used to loosen it.
The size wrench to remove it should be 15mm.
It seems to me I use a 15 mm wrench to remove the engine oil drain plug.
13mm
I can't remember exactly but its big (for a drain plug) somewhere around 17 or 19mm.
My 92 has a 9/16 size plug My 1997 LeSabre has a 15mm drain plug.
15mm
15mm.
14mm
11/16th
Use a proper size box-end wrench or socket to remove the oil drain plug