It takes alot. I just fill to 6 quarts. It always go right to the max. This is only if you are replacing the oil filter to though.
According to the 2002 Mercury Cougar Owner Guide : The 2.5 liter V6 engine takes : With engine oil filter change : ( 5.5 litres / 5.8 US. quarts of 5W-20 engine oil )
near the oil filter
14mm
For a Mercury Cougar , 2.5 litre V6 engine : According to the 1999 to 2002 Owner Guides : ( Motorcraft FL-820 engine oil filter )
According to the 2001 Mercury Cougar Owner Guide : For the 2.0 litre four cylinder engine : ( with engine oil filter change , 4.25 litres / 4.5 U.S. quarts of 5W-20 engine oil )
On a 1991 Mercury Cougar : The oil pump is INSIDE the oil pan ( the oil pan is bolted to the bottom of the engine )
I'm assuming it is the same as the ( 1996 ) Mercury Cougar 4.6 liter V8 : With engine oil filter change : ( 5.0 U.S. quarts should put you almost to the full mark )
According to the 2002 Mercury Cougar Owner Guide : With engine oil filter change : The 2.0 litre four cylinder engine takes ( 4.5 U.S. quarts ) The 2.5 litre V6 engine takes ( 5.8 ) * 5W-20
The oil capacity should be with the filter 5.5 L ( 5.8 qts )Without filter 5.0 L( 5.3 qts ).
According to the Owner Guide : With engine oil filter change : 5.0 quarts ( 4.7 liters ) of engine oil
According to the 2002 Mercury Cougar owner Guide ( 5W-20 ) With engine oil filter change : The 2.0 litre four cylinder engine takes ( 4.5 US. quarts of 5W-20 ) The 2.5 litre V6 engine takes ( 5.8 US. quarts of 5W-20 )
2.5 V6 5 liters without the oil filter.. 5,5 liters with the oil filter 2.0 similarly: 3.75 4.25 This data is from the genuine owners guide