14mm
I believe it's either a 40 or 45.
You need an oil change.
with a socket & wrench
Well, I know that on a 2000 merc cougar, if you press and hold the "Select" and "Units" buttons at the same time, it will reset the light. Hopefully this helps.
I needed a Hex 9MM worked great
15mm wrench. righty tighty, lefty loosy. so turn it counter-clockwise... dont forget the oil filter
According to the 2001 Mercury Cougar Owner Guide : The wrench light in the overhead warning lights means : ( routine maintenance should be performed , the light comes on after approximately 4800 miles / 358 days )
You need a 7 m Allen key for that year Cougar. -Of course that key is not commonly in Allen sets, so be prepared to buy one on it's own at a good tool store.
You need a 15 mm regular wrench.
Metric Allen wrench.
It will be a 14 or 17 mm wrench.
With a 13/16 open end wrench.