Since the first model year of the Mercury Mountaineer is the 1997 model it would be ( r134a )
It uses R134 refrigerant.
Use a hammer
On a 1997 Mercury Mountaineer : ( 5W-30 ) for the 5.0 liter / 302 cubic inch V8 ( with filter change , 5.0 U.S. quarts / 4.7 litres of engine oil ) According to the Owner Guide
Your 1997 Mercury Mountaineer came from the factory with ( Motorcraft MERCON automatic transmission fluid ) in your 4R70W automatic transmission ( the type that you are supposed to use should be engraved in your automatic transmission fluid dipstick just to confirm )
On a 1997 to 2001 Mercury Mountaineer : Check the Vehicle Emissions Control Information ( VECI ) decal located in the front of your engine compartment . It shows what type of spark plug to use and the spark plug gap
5w-30 would work best. If you prefer a heavier oil, you could also use 10w-30.
According to the 1997 Mercury Mountaineer owners manual : Your 4R70W automatic transmission takes ( Motorcraft MERCON automatic transmission fluid ) * the type that is used should be engraved into your automatic transmission fluid level dipstick *
A 1998 Mercury would use R134a refrigerant.
Yes
R134
Mercon V