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The Ultimate 6.6L LLY Duramax Maintenance Guide & Service Schedule

2004-2006 6.6L LLY Duramax Maintenance Guide

In a few, short years the Duramax made a name for itself. It was more powerful, capable, and reliable than GM’s previous trucks. When the LLY Duramax replaced the LB7, it offered several improvements. It also posted improvements in tow capacity, horsepower, and torque. Like the LB7, the LLY Duramax can last a very long time if taken care of properly. That means you need to follow the proper service schedule and use the right parts. If you maintain your LLY by yourself, you can also save yourself hundreds of dollars. What if you’re not familiar with these trucks though? We take the guess work out of the equation. All you need to do is follow our comprehensive 6.6L LLY Duramax Maintenance Guide. It’ll give you the know-how to successfully maintain your LLY Duramax by yourself.

Duramax on the track at UCC2019

6.6L LLY Duramax Service Schedule

How Often Should I Service My LLY Duramax?

How often you should service your 6.6L LLY Duramax is going to depend on how much you use it, and what you use it for. Excessive idling, heavy towing, or off-roading will result in the need to perform service more regularly. You should follow the severe service schedule. If you tow mostly light loads or use the truck for mostly commuting, you should use the normal operating conditions service schedule. If you don’t hit the mileage requirements, check your owner’s manual for the specific time period in which you should change your fluids and filters. Change your LLY’s engine oil and filter at least once every 6 months and your fuel filters once a year. Keep an eye on your air filter and change it as needed. If you’re in very dusty areas you will likely need to change it sooner.

Normal Operating Conditions

Maintenance/ServiceMilesKilometers
Change Oil10,000 miles16,000 Km
Change Oil
Filter
10,000 miles16,000 Km
Change Fuel
Filter
15,000 miles24,000 Km
Replace Air
Filter
As needed or every
30,000-45,000 miles.
48,000-72,000 Km
Flush Cooling
System
150,000 miles240,000 Km
Replace Auto
Transmission
Fluid
50,000 miles80,000 Km
Change External
transmission filter
50,000 miles80,000 Km
Change internal
transmission filter
50,000 miles80,000 Km
Replace Transfer
Case Fluid
50,000 miles80,000 Km
Replace Rear
Differential Fluid
100,000 miles or immediately
if submerged in water.
160,000 Km
Replace Front
Differential Fluid
100,000 miles or immediately
if submerged in water.
160,000 Km

Severe Operating Conditions

Maintenance/ServiceMilesKilometers
Change Oil5,000 Miles8,000 Km
Change Oil
Filter
5,000 Miles8,000 Km
Change Fuel
Filter
15,000 Miles24,000 Km
Replace Air
Filter
45,000 Miles***
Depends on
Conditions
72,000 Km
Flush Cooling
System
150,000 miles240,000 Km
Replace Transmission
Fluid
25,000 Miles40,000 Km
Change External
transmission filter
25,000 Miles40,000 Km
Change internal
transmission filter
25,000 Miles40,000 Km
Replace Transfer
Case Fluid
50,000 Miles80,000 Km
Replace Rear
Differential Fluid
50,000 Miles80,000 Km
Replace Front
Differential Fluid
50,000 Miles80,000 Km

Keep in mind there are other vehicle features you need to check and possibly replace. Every service you should be checking and rotating your tires. You also need to inspect all suspension and steering components and make sure they are properly lubricated or greased. Front end failures are one of the most common LLY Duramax problems.

What Do I Need to Check Every Time I Service my Truck?

Here’s a little checklist of things you need to do check time your perform maintenance on your LLY Duramax.

  • Check all areas and components holding fluid or oil for leaks
  • Check tires for signs of leaks, damage, dry rot, or uneven wear.
  • Inspect All suspension and steering components for signs of play or torn boots/seals etc…
  • Check your air filter to see if it needs to be changed.
  • Check transmission dipstick and smell the fluid. See the quality of fluid or if it smells burnt.
  • Check all suspension/steering and other truck components that need regular lubrication or greasing. If needed, add lubricant or grease.

LLY Duramax Fluid/Oil Capacity Guide

Oil/FluidCapacity – QuartsCapacity – Liters
Engine Oil10 Quarts /w Filter9.5 Liters
Auto Transmission Fluid7.4 Quarts service refill
12.7 Quarts total capacity
7 Liters
12 Liters
Manual Transmission Fluid6.3 Quarts6 Liters
Auto Transfer Case2.0 Quarts1.9 Liters
Manual Transfer Case2.0 Quarts1.9 Liters
Coolant22.0 – 31.4 Quarts20.8-29.7 Liters
Front Differential Fluid1.8 qts1.7 Liters
Rear Differential Fluid3 – 4.3 qts 2.8-4.1 Liters

Best 6.6L LLY Duramax Fluids, Oil, and Filters

Part TypePart #
Engine Oil15W-40 in temperatures above 0 Degrees F
Shell Rotella T4 15W-40
Shell Rotella T6 15W-40
Engine Oil FilterACDelco PF2232
Fuel FilterACDelco TP3018
Engine Air Filter
2004-2005
2006
See Below
ACDelco A1618C
ACDelco A3087C
Coolant50/50 mixture of Dex-Cool
12346290
and Water
Water Pump
2004-2005
2006
See Below
GM 97228188
GM 12637105
Water Pump Cover
2004-2005
2006
See Below
GM 97228188
(Comes with Water Pump)
Auto Transmission Fluid
04-05 5-Speed
06 6-Speed
See Below
Dexron III AC Delco 10-9243
Dexron VI AC Delco 10-9243
Manual Transmission Fluid
ZF S6-650 6-Speed
GM TranSynd full synthetic transmission
fluid – GM 12378515
External Transmission
Filter (Automatic)
ACDelco TF950
Internal Transmission
Filter (Automatic)
5-Speed Auto
6-Speed Auto
CHECK BELOW
——————-
GM 29537965
ACDelco TF920
Transmission pan
gasket
ACDelco 29549684
Transfer Case Fluid
Automatic
Manual
See Below
AUTO-TRAK II GM 12378508
Dexron VI ACDelco 10-9243
Front Differential FluidSAE 80W-90 Axle Fluid
Rear Differential FluidSAE 75W-90 Synthetic Axle Fluid
Diesel Exhaust FluidN/A

Commonly Used LLY Duramax Service Parts

Part NamePart #
Injector Wiring HarnessGM 98017958
Head Gasket LeftGM 12637785
Head Gasket RightGM 12637788
Head Studs Stock-500 HP ARP 230-4201
500 HP + ARP 230-4202
EGR Valve
2004.5-05
2006
Varies by Year
GM 97303761 or ACDelco 2142109
EGR Cooler
2004.5-05
2006

LLY Duramax Steering/Suspension Replacement Parts

LiftBilstein 5100Bilstein 5160
Reservoir
LiftFox 2.0
Performance
Fox 2.0
Reservoir
0-2″
24-18673525-1876180-1″980-24-663980-24-959
4-6″24-18718325-1876874-6″980-24-658980-24-960
6-8″33-186542N/A7-9″980-24-962980-24-961
Maintenance/ServiceGMKryptoniteMoogCognito
Pitman Arm 3 Spline
Pitman Arm 4 Spline
19168473KR6654
KR6536
K6654HD
K6536HD
Idler Arm10KDG535K6535HD
Upper Ball Joint
(Stock UCAS)
KR6696K6696
Lower Ball Joint
(Stock LCAS)
19207137KR6693K6693
Complete Ball Joint
set
0110BJPACK
Upper Control Arms25905442KRUCA10CK620054
Lower Control Arms
Left
Right
See Below
20832022
20832023
N/ASee Below
RK621356
RK621355
Torsion KeysKRKEY10K100012
Torsion Key Bolts
Tie Rod KitKRTR10110-90285
Tie Rod End (inner)10KXDI34
10KXDI78
ES3488
Tie Rod End (Outer)10KL34
10KL78
ES3609
Center Link
Without Hole
for steering
stabilizer
KRCLP10DS300059A
Center Link With
Hole for steering
stabilizer
N/ADS300011

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