rings or seals
That would be the 4.6 liter engine, which takes six quarts. * of 5W-20 according to the 2003 Mercury Mountaineer Owner Guide
Bank 1 is the passenger side of the engine in your Mercury Mountaineer Sensor 1 would be close to the engine before the exhaust enters the catalytic converter ( upstream sensor )
On a 2002 Mercury Mountaineer ( V6 and V8 engines ) Bank 2 is the drivers side of the engine Sensor 1 would be close to the engine BEFORE the exhaust enters the catalytic converter
Since the first model year of the Mercury Mountaineer is the 1997 model it would be ( r134a )
I'm not a mechanic / technician , but I would say ( no ) if you mean the six cylinder engine The 1996 Ford Explorer V6 is the 4.0 literEFI ( which is an Over Head Valve / pushrod design engine ) The six cylinder engine in a Mercury Mountaineer has always been the 4.0 liter Single Over Head Cam ( SOHC ) version
Mercury poisoning.
An ABS fault.
Pin cone
Your engine oil could be low check it when it cools and if level is fine your oil pressure sending unit could be bad or engine in need of rebuilding
if you go to any auto parts store they have repair manuals that show you how to take apart and put back together your specific vehicle, has photos. would find mountaineer in a ford explorer book. cost about $20, but are worth it.
On a 1997 Mercury Mountaineer : I assume the fuel filter would be in the same location as a 1997 Ford Explorer : ( underneath the Mountaineer , below the drivers door , mounted on the frame rail )
bearning on front breaks burn out