6.9L & 7.3L IDI Diesel Maintenance Schedule

Service Intervals & Information for 6.9, 7.3 IDI Diesels

Applicable Models:

1983 - 1994 Ford F-250, F-350, F-450, F-Super Duty

Applicable Engine(s):

International 6.9L IDI V-8 diesel, International 7.3L IDI V-8 diesel, turbocharged & naturally aspirated variants

For the purpose of service intervals, "severe" driving conditions are defined as any combination of the following:

• Excessive idling (more than 10 minutes of idling per hour of driving)
• Frequent short trips or start-shutdown cycles in which the engine does not reach full operating temperature
• Driving in dusty environments
• Driving off-road or in conditions that require the use of 4 wheel drive
• Frequent towing or hauling

6.9L, 7.3L IDI Service Intervals

Note - Select service intervals represent an adaptation of Ford's OEM recommendations that account for procedures not listed in the original owners manual/diesel supplement.



Replace engine air filter

30,000 miles regardless of condition
Check at oil change intervals, replace as necessary

Replace engine oil & oil filter

5,000 miles or 6 months under normal driving conditions
2,500 miles or 3 months under severe driving conditions

Drain fuel water separator

5,000 miles
6.9L IDI water separator located on driver side firewall
7.3L IDI water separator integrated into fuel filter assembly

Replace fuel filter

15,000 miles under normal driving conditions
7,500 miles under severe driving conditions

Check & adjust drive belt tension

15,000 miles (models with non-serpentine belt only, i.e. no belt tensioner)

Inspect crankcase depression
regulator valve (CDR)

30,000 miles
Suggest replacing every 60,000 miles regardless of condition

Check coolant condition

Annually test for proper SCA/DCA level under normal conditions
More frequent inspection is advised under severe driving conditions

Flush & replace engine coolant

36 months regardless of mileage

Replace automatic transmission
fluid & filter

30,000 miles

Replace manual transmission fluid

60,000 miles

Replace transfer case fluid

60,000 miles (more frequent service advised if 4 wheel drive used frequently)
Replace immediately anytime transfer case is submerged

Replace front differential fluid (4x4)

100,000 miles under normal driving conditions
30,000 miles under severe driving conditions
Replace immediately anytime differential is submerged

Replace rear differential fluid

100,000 miles under normal driving conditions
30,000 miles under severe driving conditions
Replace immediately anytime differential is submerged

6.9L, 7.3L IDI Service Part Numbers

Note - All part numbers listed applicable to Ford F-Series trucks (F-250/F-350/F-Super Duty). Select part numbers may not be compatible with engines found in E-Series/Econoline vans; always verify compatibility with your parts specialist.

Part Description

Part Number(s)

Engine air filter

6.9L, 7.3L IDI, naturally aspirated

Motorcraft FA-1057 (Ford E7TZ-9601-A)

7.3L IDI, factory turbo

Motorcraft FA-1605 (Ford F3TZ-9601-Z)

Engine oil filter

Motorcraft FL-784

Engine oil fill cap

Stant 11066 (Supersedes 10066)

Fuel filter

6.9L IDI

Motorcraft FD-811
Donaldson P550811

7.3L IDI

Motorcraft FD-3375
Donaldson P559852 (kit w/ bowl & drain valve)

Crankcase depression regulator (CDR) valve

Ford E3TZ-6A665-A (listed as "adapter" by Ford)

CDR valve grommet/gasket

Ford E3TZ-6A892-A

Fuel Lift pump (low pressure)

Carter M60278 (mechanical lift pump, engine block mounted)

Glow plug

6.9L IDI

Motorcraft ZD1A (Ford E5TZ-12A342-B)

7.3L IDI

Motorcraft ZD9 (Ford F2TZ-12A342-A)

Glow plug controller

6.9L IDI

Motorcraft SW5241

7.3L IDI

Ford E7TZ-12B533-A

Glow plug relay

Motorcraft DY-861 (7.3L IDI only)


Motorcraft RT-1049 (Ford E5TZ-8575-C)

Thermostat housing gasket

Motorcraft RG-531 (Ford E3TZ-8255-A)

Radiator cap

Stant 10229


Motorcraft VC-8 or Fleetguard DCA4 DCA60L
Use with test strips Fleetguard CC2602A to maintain SCA/DCA concentration

Engine oil cooler assembly

Ford F3TZ-6A642-C

Engine oil cooler o-rings [1]

Large o-ring

Ford 1C3Z-6C610-BA

Small o-ring

Ford 1C3Z-6K649-BA

Engine oil cooler header gaskets

Ford F7TZ-6A636-AAA (front)
Ford F4TZ-6A636-A (rear)

Automatic transmission filter

C6, 3 spd

Motorcraft FT-52 (Ford D5AZ-7A098-B)

AOD, 4 spd

Motorcraft FT-58 (Ford E1AZ-7A098-A)

2WD E4OD, 4 spd

Motorcraft FT-113 (Ford YC3P-7G186-AB)

4WD E4OD, 4 spd

Motorcraft FT-114 (Ford YC3Z-7A098-AA)

[1] 1983/1984 model year 6.9L diesels may have a 6 o-ring oil cooler which requires (4) small and (2) large oil cooler o-rings. Later 6.9L diesels and all 7.3L IDI diesels require (2) small and (2) large o-rings.

6.9L, 7.3L IDI Fluid Specs & Capacities


Oil/Fluid Specification

Oil/Fluid Capacity [1]

Engine oil

Ambient temp > 0° F

SAE 15W-40
Recommend Amsoil Heavy Duty 15W-40 synthetic diesel oil [2]

10 quarts w/ filter

Ambient temp < 60° F

SAE 10W-30
Recommend Amsoil Heavy Duty 10W-30 synthetic diesel oil

Ambient temp > 30° F

SAE 30

Engine coolant

50/50 mixture of ethylene glycol engine coolant and distilled water
Motorcraft green VC-5 engine coolant (concentrate)
Motorcraft green VC-5DIL engine coolant (pre-mixed)
Motorcraft VC-8 SCA/DCA [3]

7.25 - 7.75 gallons

Automatic transmission [4]

C6 (3 spd)

MERCON V automatic transmission fluid [5]
Ford/Motorcraft XT5QMC MERCON V ATF

12 - 13.5 quarts

AOD (4 spd)

12.25 quarts

E4OD (4 spd)

13.5 quarts

Manual transmission

T-19 (4 spd)

50W engine oil or 80W-90 non-hypoid gear oil

3.5 quarts

ZF S5-42 (5 spd)

MERCON V automatic transmission fluid [5]
Ford/Motorcraft XT-5-QMC MERCON V ATF
Recommend Amsoil OE synthetic ATF

3.38 quarts

Hydraulic clutch system

DOT 3 brake fluid
Motorcraft PM-1-C DOT 3


Transfer case

BorgWarner BW1345

MERCON LV automatic transmission fluid [6]
Ford/Motorcraft XT-10-QLVC MERCON LV ATF
Recommend Amsoil OE fuel-efficient synthetic ATF

3.25 quarts

BorgWarner BW1356

2 quarts

Front differential

Dana 50 TTB (IFS)

SAE 80W-90 gear oil
Recommend Amsoil Severe Gear 80W-90 synthetic gear oil

2 quarts

Dana 60 (solid)

3 quarts

Rear differential [7]

Sterling 10.25

SAE 75W-140 full synthetic
Recommend Amsoil Severe Gear 75W-140 synthetic gear oil

3.25 - 3.50 quarts

Dana 80

4.2 quarts

Dana 70

SAE 80W-90 gear oil
Recommend Amsoil Severe Gear 80W-90 synthetic gear oil

3.25 - 3.7 quarts

Dana 60

3 quarts

[1] All oil and fluid capacities are nominal; always fill to proper dipstick, fill plug, or indicator level and verify proper oil/fluid level before operating vehicle.
[2] For high mileage engines, consider a high TBN engine formulation such as Amsoil 15W-40 Heavy Duty TBN 12 synthetic diesel oil. The higher TBN level will counteract acids produced by blowby contamination, keeping the PH level of the engine oil balanced for a longer duration. Amsoil full synthetic diesel oils are premium products that typically reduce fuel dilution and oil consumption in aging diesel engines.
[3] Supplemental coolant additive/diesel coolant additive (SCA/DCA) required to prevent cavitation. Use per instructions and periodically test and adjust SCA/DCA level to prevent cavitation in 7.3L IDI diesels.
[4] Total fluid capacity listed for all automatic transmissions; service refill capacity will be much less.
[5] MERCON V supersedes original MERCON automatic transmission fluid specification.
[6] MERCON LV supersedes original MERCON ATF and previous XL-12 transfer case fluid specification. Do NOT use MERCON V in transfer cases. Recommend Amsoil OE fuel efficient ATF, a high performance alternative that meets or exceeds Ford MERCON LV spec for transfer cases.
[7] Limited slip differentials may require Motorcraft XL-3 friction modifier to prevent differential chatter; use (1) 4 oz bottle.