Two options. Because there's two system designs.
Either A: It's on the top of the radiator on either the far right or far left corner.
OR B: It is a screw on cap on what looks like a plastic overflow jug, but BEWARE, if the system is hot or under pressure it WILL blow off very fast just like an older normal system.
The engine in a 1993 grand marquis is a 4.6 litre/281 cubic inch.
On a 1993 Mercury Grand Marquis : The electric fuel pump is INSIDE the fuel tank
5W-30
Try Autozone.com - they very likely have an on-line illustrated repair guide for the '93 Grand Marquis.
Let the handy man at it,
There could be many reasons why the 1993 Grand Marquis make noises when the doors lock. The wiring could be off, or the motor could be going out.
If it has one it will be located on the bottom of the radiator. If not, then just remove the lower hose to drain the radiator.
The cap is on the coolant reservoir (driver's side behind the battery), not on the radiator itself as in many other vehicle makes. Mine is yellow. DO NOT remove cap if engine/coolant is hot as system is pressurized.
On my '93, there is no consumer serviceable port. I think the recharge has to be done by a technician.
Bad head gasket? Bad thermostat? Defective radiator cap?
The colors are irrelevant, just use any 50/50 mix & you will be ok.
P215/70R15 for 93 and i think for a 00 P225/60TR17