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2003 Buick Regal

Factory specifications, fluid capacities, torque values, EPA fuel economy and the federal safety record for the 2003 Regal.

Body PASSENGER CARTransmission Automatic 4-spd

The 2003 Buick Regal is a midsize passenger car equipped with a 4-speed automatic transmission, requiring 4.5 quarts of 10W-30 API-grade motor oil, and rated by the EPA at 16 mpg city, 25 mpg highway, and 19 mpg combined — figures that positioned it competitively within its segment for the model year. In terms of reliability, the 2003 recorded 104 owner complaints, with the electrical system emerging as the primary concern alongside five total recalls, placing it well below the model's 1998 peak of 325 complaints but significantly above the historically low complaint rate the brand would achieve by 2008. This positions the 2003 Regal as a transitional model in the nameplate's history, reflecting the kind of mid-cycle refinement issues that were common among GM products of this era while still representing a notable improvement from the problematic late-1990s period.

Model year2018 2017 2016 2015 2014 2013 2012 2011 2003

Quick specs

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

Engine oil capacity4.5 qtOEM · verified

Engine oil type10W-30 APIOEM · verified

Lug nut torque100 ft-lbsOEM · verified

EPA fuel economy16/25/19 mpgEPA · verified

Fitment & sizes

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

From the factory this vehicle uses a BCI 78 supercharged · 770 supercharged CCA battery, OE oil filter 12731175. Note the factory fuel filter is now discontinued — plan on a superseded or quality aftermarket equivalent, which the part pages below list where known. Each part links to every other vehicle that shares it, so a part you already stock may fit more of your fleet than you'd expect.

Battery groupBCI 78 supercharged · 770 supercharged CCAOEM · verified

Tire sizeP215-70R15OEM · verified

OE service part numbers OEM · verified

Engine oil filter	12731175
Engine air filter	15221217
Fuel filter	25121293 discontinued
Spark plug	12681664
Front wiper blades	19120758
Serpentine belt	19244951 alt 12588411
Thermostat	24505924 alt 24506985
Cabin air filter	84557894

Full specifications

Engine, drivetrain, dimensions and economy.

Engine & drivetrain NHTSA vPIC

Transmission

Automatic 4-spd

Dimensions & weight NHTSA vPIC

Overall length	196.1 in
Overall width	72.8 in
Overall height	56.7 in
Wheelbase	109.1 in
Curb weight	3446 lb
Track (front / rear)	62.2 / 61.4 in
Weight distribution (front / rear)	63/37

Ratings & economy EPA / vPIC

EPA city / highway / combined	16 / 25 / 19 mpg
Drivetrain	Front-Wheel Drive
Passenger volume	102 cu ft
Cargo volume	17 cu ft
Recommended fuel	Premium Gasoline

Performance & power Independent road tests

0–60 mph, quarter-mile, horsepower and torque from independent road tests.

Independent road tests for the Regal of this era, listed by trim and engine — this page spans more than one engine, so no single horsepower figure is shown.

6.2–9.4 sec0–60 mph (tested)quickest 6.20 sec — 2012 GS Sedan

Year	Trim / engine	0–60	¼ mile	HP	Drivetrain
2002	LS Sedan 3.8L V6	8.10 sec	16.30 sec	200 hp	FWD
1998	GS Sedan 3.8L Supercharger V6	6.70 sec	15.10 sec	240 hp	FWD
1997	GS Sedan 3.8L Supercharger V6	6.60 sec	15.00 sec	240 hp	FWD
1997	LS Sedan 3.8L V6	7.80 sec	16.00 sec	205 hp	FWD
1995	Gran Sport Coupe 3.8L V6	8.20 sec	16.00 sec	205 hp	FWD
2011	CXL Turbo Sedan 2.0L Turbo I-4	6.80 sec	15.40 sec	220 hp	FWD
2011	CXL Turbo Sedan 2.0L Turbo I-4	7.50 sec	15.70 sec	220 hp	FWD
2011	CXL Turbo Sedan 2.0L Turbo I-4	7.50 sec	15.70 sec	220 hp	FWD

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 API engine oil. Torque lug nuts to 100 ft-lbs, the oil drain plug to 18.0 ft-lbs. The firing order is 1-6-5-4-3-2.

Lubricants & capacities

Engine Oil	10W-30 · API
Engine Oil Capacity	4.5 qt

Engine torques

Intake Manifold to Engine Bolts	Lower: 11 ft-lbs; Upper: 7.4 ft-lbs
Exhaust Manifold to Cylinder Head Bolts	22 ft-lbs
Engine Oil Pan Drain Plug	18.0 ft-lbs
Engine Valve Cover Bolts	7.5 ft-lbs

Chassis torques

Lug Nuts	100 ft-lbs
Front Wheel Hub	159 ft-lbs

Ignition

Cylinder Firing Order	1-6-5-4-3-2
Ignition Coil Secondary Resistance	5,000-8,000 ohms
Spark Plug Manufacturer	AC Delco
Spark Plug Type	AC 41-921
Spark Plug Gap	0.060 in
Spark Plug Torque	11.0 ft-lbs

Battery & A/C

Refrigerant	R134a
Refrigerant Capacity	2.20 lbs
Oil Group	PAG
Oil Type	46
Oil Capacity	9.00 oz
Standard BCI Group Number	78 supercharged
Standard BCI Cranking Performance	770 supercharged cca

Service checks

Pressure Test	15; Do not exceed 20 psi.
Radiator Cap Pressure Relief	15 psi
Thermostat Opening Temperature	188-206 °F
Key ON Engine OFF (KOEO)	48-55
RPM	38-52 @ Idle rpm
Key ON Engine OFF (KOEO)	48-54
Injector Primary Resistance	11-14 @ 70 degreesF ohms
Engine Compression	100

Brakes

Torque Caliper to Bracket	133 ft-lbs / 32 ft-lbs
Torque to Knuckle	100 ft-lbs / 8 ft-lbs
Minimum Pad Thickness	Front: 0.030; Rear: 0.030 specification
Rotor Max Parallel Variation	0.001 in
Rotor Runout Limit	0.002 in
Rotor Nominal Thickness From	1.27 in / 0.43 in
Rotor Nominal Thickness To	1.27 in / 0.43 in
Rotor Minimum Machining	1.224 in / 0.39 in

Multi-step torque procedures OEM · verified

Crankshaft Pulley and/or Damper Bolts — tightening sequence 1 stages

111 ft. lbs., step 2: 76

111 ft. lbs

Cylinder Head — tightening sequence 2 stages

1	37 ft. lbs.	37 ft. lbs
2	120

Cylinder Head — tightening sequence 2 stages

1	37 ft. lbs.	37 ft. lbs
2	120

Factory maintenance schedule OEM · verified

Normal service, condensed from the factory interval matrix.

Under the factory schedule, replace the spark plugs every 100,000 mi; coolant at 150,000 mi. The big-interval services (at 150,000 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.

Every 7,500 mi	Tire & Wheel Assembly (rotate)
Every 15,000 mi	Cabin Air Filter (replace)
Every 30,000 mi	Engine Air Filter Element (replace) · Supercharger Assembly (inspect fluid level)
Every 100,000 mi	Spark Plug Wires (inspect) · Spark Plugs (replace) · Transmission Fluid & Filter (replace)
At 150,000 mi	Accessory Drive Belt (inspect) · Engine Coolant System (drain, flush & refill)

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 2003 Buick Regal sits near the end of its generation’s federal-record arc, after complaints peaked at 325 in 1998 and then trended steadily downward through 1999, 2000, 2001, and 2002. For 2003 specifically, NHTSA shows 104 complaints, 5 recalls, 0 investigations, and 441 TSBs—meaning complaints and recalls are lower than in 2001 and 2002, investigations have disappeared, but TSB volume is at its generation high. The 2004 model follows with even fewer complaints (66) and recalls (4), so 2003 is not the absolute cleanest year but is clearly part of the generation’s late-run improvement. Complaints cluster in the electrical system (26), engine (17), engine and engine cooling (10), and wheels (5), with 14 fire-related complaints and 5 crash-related complaints; the data does not specify root causes for those incidents. Given the declining complaint and recall trend and zero investigations, a well-documented 2003 Regal is a comparatively good year to buy within this generation, provided you verify prior service for electrical and engine items and review any history tied to the fire complaints.

Open recalls

NHTSA campaigns

441

Service bulletins

Manufacturer communications

ODI investigations

Office of Defects Investigation

104

Owner complaints

5 involved a crash · 14 a fire

Owner complaints by model year NHTSA · this generation & adjacent

’90 ’91 ’92 ’93 ’94 ’95 ’96 ’97 ’98 ’99 ’00 ’01 ’02’03’04 ’05 ’08 ’09 ’10 ’11 ’12 ’13 ’14 ’15 ’16 ’17 ’18 ’19 ’20

Owner complaints filed with NHTSA, by component

All 104 complaints on record, top 8 components.

Electrical System26

Engine17

Engine & Engine Cooling10

Wheels5

Exterior Lighting4

Steering4

Power Train3

Seats2

Source: NHTSA Office of Defects Investigation complaint database.

Recalls NHTSA · verified

Showing 2 of 5 campaigns on record for this vehicle.

15V701000Engine And Engine Cooling:EngineReported 26/10/2015

General Motors LLC (GM) is recalling certain model year 1998-1999 Chevrolet Lumina and Oldsmobile Intrigue, 1997-2004 Buick Regal and Pontiac Grand Prix, 2000-2004 Chevrolet Impala, and 1998-2004 Chevrolet Monte Carlo… Remedy: The remedy applied under recalls 08V-118, 09V-116, and 15V-201 did not adequately remove the safety risk. Under the improved remedy, dealers will replace the engines front valve…

09V116000Engine And Engine CoolingReported 08/04/2009

GENERAL MOTORS IS RECALLING 1,497,516 MY 1997-2003 BUICK REGAL, MY 1998-2003 CHEVROLET LUMINA, MONTE CARLO AND IMPALA, MY 1998-1999 OLDSMOBILE INTRIGUE, MY 1997-2003 PONTIAC GRAND PRIX VEHICLES EQUIPPED WITH A 3.8L V6… Remedy: DEALERS WILL REPLACE THE ENGINES FRONT VALVE COVER AND FRONT-VALVE-COVER GASKET WITH NEW PARTS OF AN IMPROVED DESIGN AND REMOVE THE ENGINES PLASTIC COVER AND PLASTIC…

Technical service bulletins NHTSA · verified

Showing 5 of 441 bulletins on record with NHTSA.

Bulletin	Date	Component	Summary
PIP5601C	2025-07-18	Unknown Or Other	This PI communicates the requirement to provide a pico file to receive diagnostic…
PIP5358D	2025-02-19	Unknown Or Other	This Preliminary Information communication provides information to the technician about…
PIP4723J	2024-10-25	Electrical System	This Preliminary Information communicates to the dealer the process for downloading or…
PIT5099H	2024-09-12	Unknown Or Other	This Preliminary Information communication provides information to the technician about…
PIT5099H	2024-09-12	Unknown Or Other	This Preliminary Information communication provides information to the technician about…

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 Regal. 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.

Group 78 battery Vehicles taking 4.5 qt Engine oil filter 12731175 Engine air filter 15221217 Fuel filter 25121293 Spark plug 12681664

Reference guides

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

Vehicle recalls & TSBs OBD-II trouble codes Torque specifications Maintenance schedules Fluid capacities & specs

Frequently asked

How much oil does the 2003 Regal take?

4.5 qt of 10W-30 API, per the factory manual.

Does the 2003 Regal have open recalls?

NHTSA lists 5 recall campaign(s) for this model year. Check your specific vehicle by VIN.

What gas mileage does the Regal get?

EPA figures are 16 city / 25 highway / 19 combined mpg.