On a 1991 Mercury Cougar :
The oil pump is INSIDE the oil pan
( the oil pan is bolted to the bottom of the engine )
with a socket & wrench
According to my Chilton's Auto Repair Manual : For the 3.8 liter V6 engine in a 1991 Mercury Cougar : With engine oil filter change : ( 5.0 US. quarts )
I have a 1994 Mercury Cougar that runs good but burns alot of fuel and after the engine starts the and gets some heat, oil pressure gauge indicates low when there is nothing wrong. I have the same problem with a 1991 Mercury Cougar 3.8, doesn't burn fuel that much but a mechanician told me that it might be a miscontact on the gauge indicator, some dirt in oil pan blocking oil pump or the oil pump is going off. First thing to do is changing oil and filter replacing it by syntec oil in it so it will stay in engine more time when heating. If after that nothing changed check oil pressure at a local garage.
5w 30
5w30
near the oil filter
On a 1991 Mercury Capri, the oil pump is located in the oil pan assembly, which is situated at the bottom of the engine. To access the oil pump, you typically need to remove the oil pan, as it is mounted on the engine block and driven by the crankshaft. It's advisable to consult the vehicle's service manual for detailed instructions and specifications if you're planning to inspect or replace the oil pump.
with your eyes
You need an oil change.
Mercon V
According to the 2000 Mercury Cougar owners manual ( 5W-30 ) for the four cylinder and V6 engines
For a Mercury Cougar , 2.5 litre V6 engine : According to the 1999 to 2002 Owner Guides : ( Motorcraft FL-820 engine oil filter )