MercuryGrand Marquis1991Overview/mercury/grand-marquis/1991/base/

1991 Mercury Grand Marquis

Factory specifications, fluid capacities, torque values, EPA fuel economy and the federal safety record for the 1991 Grand Marquis.

Transmission Automatic 4-spd

The 1991 Mercury Grand Marquis, equipped with a 4‑speed automatic transmission and a 4.5‑quart oil capacity, delivered EPA‑rated fuel economy of 15 mpg city, 22 mpg highway, and 18 mpg combined. This model year recorded 90 total owner complaints, with the electrical system as the top concern, and two recalls were issued. Within the model’s complaint history spanning 1990 to 2011, the 1991 Grand Marquis sits early in the timeline, with a complaint count well below the 2005 peak of 487 but above the 2011 low of 9, reflecting a moderate reliability record for its era.

Model year201120102009200820072006200520041991

Quick specs

Fluid capacities, tune-up values and fuel economy at a glance.

Engine oil capacity4.5 qtOEM · verified
Engine oil type10W-30 / 5W-30OEM · verified
EPA fuel economy15/22/18 mpgEPA · verified

Fitment & sizes

Replacement part sizes and factory part numbers — battery, bulbs, filters and belts.

OE service part numbers OEM · verified

Serpentine beltD9PZ8620H
ThermostatRT1052 discontinued

Full specifications

Engine, drivetrain, dimensions and economy.

Engine & drivetrain NHTSA vPIC

TransmissionAutomatic 4-spd

Dimensions & weight NHTSA vPIC

Overall length218.1 in
Overall width79.1 in
Overall height56.7 in
Wheelbase114.2 in
Curb weight4015 lb

Ratings & economy EPA / vPIC

EPA city / highway / combined15 / 22 / 18 mpg
DrivetrainRear-Wheel Drive
Passenger volume111 cu ft
Cargo volume21 cu ft
Recommended fuelRegular Gasoline

Service quick specs OEM factory data

Capacities, torques and tune-up values from the factory service manual.

This engine holds 4.5 qt of 10W-30 / 5W-30 engine oil, DOT 3 brake fluid.

Lubricants & capacities

Brake FluidDOT 3
Engine CoolantETHYLENE GLYCOL
Engine Oil10W-30 · 5W-30
Engine Oil Capacity4.5 qt

Factory maintenance schedule OEM · verified

Normal service, condensed from the factory interval matrix.

Under the factory schedule, replace the engine oil and filter every 7,500 mi; coolant every 30,000 mi. The big-interval services (every 30,000 mi for coolant, and the transmission fluid) are the ones owners most often skip — on a lower-mileage example, assume the original fluids are still in it and check them first.

At 7,500 miTire & Wheel Assembly (rotate)
Every 7,500 miEngine Oil (drain & refill) · Engine Oil Filter (replace)
Every 15,000 miPCV Valve (replace) · Steering Linkage (inspect) · Suspension System (inspect) · Tire & Wheel Assembly (rotate)
Every 30,000 miAccessory Drive Belt (inspect) · Brake Linings (inspect) · Engine Air Filter Element (replace) · Engine Breather Filter (replace) · Engine Coolant System (drain, flush & refill) · Exhaust System Heat Shield (inspect)

Reliability & federal safety record

Owner-reported issues, recalls, investigations and service bulletins on record with NHTSA — an unfiltered look at what owners actually experience.

The 1991 Mercury Grand Marquis generated 90 complaints, 2 recalls, 1 investigation, and 40 TSBs, representing a modest increase from 1990’s 61 complaints and 1 recall but remaining far below the 346 complaints and 8 investigations that arrived in 1992. Across the generation, federal filings trended sharply upward after 1991, with complaint volumes regularly exceeding 180 and eventually peaking at 487 by 2005, placing the 1991 model at the low end of an early baseline before sustained escalation. For this specific model year, the highest volume of owner reports concerned the Electrical System with 21 filings, followed by Vehicle Speed Control at 12 and Air Bags at 11, with 14 fire-related and 13 crash-related complaints recorded, though the data does not specify root causes for these incidents. Given its position before the dramatic 1992 spike and its comparatively minimal regulatory footprint relative to the rest of the generation, the 1991 Grand Marquis represents a relatively favorable year to buy.

2
Open recalls
NHTSA campaigns
40
Service bulletins
Manufacturer communications
1
ODI investigations
Office of Defects Investigation
90
Owner complaints
13 involved a crash · 14 a fire
Owner complaints by model year NHTSA · this generation & adjacent

Owner complaints filed with NHTSA, by component

All 90 complaints on record, top 8 components.

Electrical System21
Vehicle Speed Control12
Air Bags11
Engine & Engine Cooling7
Power Train7
Service Brakes, Hydraulic7
Fuel System, Gasoline4
Structure3

Source: NHTSA Office of Defects Investigation complaint database.

Recalls NHTSA · verified

Showing 2 of 2 campaigns on record for this vehicle.

91V048000Power Train:Automatic TransmissionReported 18/03/1991

THE PARK ROD ASSEMBLY CONTAINS A PARK CAM WITH INADEQUATE SURFACE HARDNESS, WHICH COULD LEAD TO PARK DISENGAGEMENT OR NO PARK ENGAGEMENT WHEN THE LEVER IS PLACED IN PARK. Remedy: REPLACE PARK ROD ASSEMBLY ON AUTOMATIC TRANSMISSIONS.

90E043001Air Bags:FrontalReported 30/10/1990

THREADED INFLATOR COMPONENTS MAY HAVE BEEN DAMAGED DURING ASSEMBLY WHICH MAY ALLOW COMPONENTS TO SEPARATE WHEN INFLATOR RECEIVES A SIGNAL TO DEPLOY THE AIR BAG. Remedy: REPLACE AIR BAG MODULES CONTAINING POTENTIALLY DEFECTIVE INFLATORS.

Technical service bulletins NHTSA · verified

Showing 5 of 40 bulletins on record with NHTSA.

BulletinDateComponentSummary
021072002-05-27VisibilityTRANSFER SERVICE TIPS FOR THE FRONT WIPER MOTOR MOUNT BRACKET AND DEPRESSED PARK OUTPUT…
011942001-10-01Electrical SystemTHIS ARITLCE IS TO PROVIDE INFORMATION ON REPLACEMENT OF OLD STYLE HOOD LAMP SWITCH TO…
011562001-08-06VisibilitySOME VEHICLES MAY EXHIBIT HEATER CORE LEAKS. *SLC
011572001-08-06Unknown Or OtherINFORMATION REGARDING TRANSMISSION FLUID USAGE CHARTS. *SLC
0112012001-06-25VisibilityTHIS INFORMATION IS A SUPPLEMENT TO THE WIPER SYSTEM SERVICE INFORMATION PROVIDED IN THE…

Common OBD-II trouble codes

The most common OBD-II codes for this vehicle's emissions system. These are standardized SAE J2012 definitions, not vehicle-specific fault reports.

P0420
Catalyst system efficiency below threshold — Bank 1
P0300
Random / multiple cylinder misfire detected
P0171
System too lean — Bank 1
P0455
Evaporative emission system leak detected — large leak
P0128
Coolant thermostat below regulating temperature
P0442
Evaporative emission system leak detected — small leak

VIN tools

Decode factory build data for a specific vehicle by VIN.

VIN
Decode a VIN to confirm the transmission and build data for a specific Grand Marquis. OEM
Build data
Plant, GVWR class, engine and body data for any 17-character VIN.
Recalls
Check open recall campaigns against a specific vehicle by VIN.

Vehicles with shared specs

Find every vehicle that shares this one's battery, bulbs, oil capacity, platform or parts.

Reference guides

Cross-vehicle references for the kinds of data on this page.

Frequently asked

How much oil does the 1991 Grand Marquis take?

4.5 qt of ABOVE 0 degrees F 10W-30, BELOW 100 degrees F 5W-30, per the factory manual.

Does the 1991 Grand Marquis have open recalls?

NHTSA lists 2 recall campaign(s) for this model year. Check your specific vehicle by VIN.

What gas mileage does the Grand Marquis get?

EPA figures are 15 city / 22 highway / 18 combined mpg.