6.6L Duramax L5P Maintenance Schedule & Service Guide | 2017 - 2022 Duramax Diesel

Applicable Models:

2017 - current Chevrolet Silverado 2500/3500
2017 - current GMC Sierra 2500/3500

Applicable Engine(s):

6.6L Duramax diesel L5P
(8th digit of VIN "Y", see Duramax VIN ID for additional information)

Applicable Transmission(s):

Allison 1000 six speed automatic, GM-Allison 10L1000 ten speed automatic

Missing the owners manual from your 2017 to 2022 Chevy Silverado or GMC Sierra? Misplaced your L5P Duramax diesel supplement? Or maybe you're in need or more comprehensive service information for your 6.6L Duramax. In any event, we've got you covered.

6.6L Duramax L5P Maintenance Schedule (Service Intervals)


Service Interval(s)


Replace engine oil & oil filter

10,000 miles or when "change engine oil" message is displayed by the oil life monitoring system


Replace fuel filter, drain water separator

22,500 miles/2 years or when "change fuel filter" message is displayed


Replace engine air filter

45,000 miles/4 years or when "replace engine air filter" message is displayed


Perform engine cooling system service

150,000 miles/5 years


Replace automatic transmission fluid & filters

45,000 miles (Allison 6 speed and GM-Allison 10 speed transmissions)


Replace transfer case fluid

50,000 miles


Replace front differential fluid

50,000 miles

[5], [6]

Replace rear differential fluid

Perform multi-point inspection

At oil change intervals


[1] Do not exceed 10,000 miles between oil changes. More frequent oil changes may be advisable if towing frequently, hauling payloads near GVWR, or idling for extended periods of time. Recommend changing engine oil every 12 months if mileage does not meet service criteria.
[2] Check air filter condition at oil change intervals and replace as necessary. Driving in dusty conditions will require more frequent air filter replacements.
[3] At minimal, drain coolant from engine cooling system and replace thermostats, upper radiator hose, lower radiator hose, and replenish with new coolant/distilled water solution. Inspect remaining hoses and overflow tank, replace as necessary. Recommend that subsequent cooling system services are performed at 50,000 mile intervals after the initial 150,000 mile service.
[4]Allison 6 speed transmission features internal and external (auxiliary) filters. GM-Allison 10 speed transmission has single external filter only.
[5] Replace transfer case and differential fluid immediately anytime these components are submerged in water; water infiltration is highly likely.
[6] No service interval provided by GM; recommend replacing front and rear differential gear oil at 50,000 mile intervals to prolong life.
[7] Multi-point inspection should include examination of ball joints, universal joints, CV joints, air filter, fuel system (leak detection), exhaust system, and vehicle brake condition. Grease applicable Zerk fittings as required.

6.6L Duramax L5P Service Parts List

Part Description

Part Number

Engine air filter

2017 - 2019 models

ACDelco A3231C

2020 - 2021 models

ACDelco A3248C

Engine oil filter

2017 - 2019 models

ACDelco PF2232

2020 - 2021 models

ACDelco PF26

Oil pan drain plug

2017 models

GM 11569943(integrated gasket)

2018 - 2021 models

GM 55577568 (gasket sold separately)

Oil pan drain plug gasket

2018 - 2021 models

GM 12616850

Oil fill cap

ACDelco FC261

Fuel filter

ACDelco TP1015

Serpentine belt, single alternator

2017 - 2019 models

ACDelco 12656797

2020 - 2021 models

ACDelco 12675892

Serpentine belt, dual alternator

2017 - 2019 models

ACDelco 6K1395A

2020 - 2021 models

ACDelco 12675893

Water pump drive belt

2020 - 2021 models

ACDelco 12675896

Thermostat, front

2017 - 2019 models

ACDelco 12T99D

2020 - 2021 models

ACDelco 131-197

Thermostat, rear

2017 - 2019 models

ACDelco 121-131

2020 - 2021 models

ACDelco 131-197

Thermostat seal

GM 98280281

Thermostat housing gasket

GM 12643149

Coolant reservoir cap

2017 - 2018 models

ACDelco RC120 or ACDelco 12R05

2019 - 2021 models

GM 13502353

Upper radiator hose

2017 - 2019 models

ACDelco 84094878

2020 - 2021 models

GM 84813629

Lower radiator hose

2017 - 2019 models

ACDelco 84401398 & ACDelco 84376513

2020 - 2021 models

ACDelco 84645096

Glow plug

ACDelco 68G

Automatic transmission filter, external

Allison 6 speed

ACDelco TF950, Allison 29539579

GM-Allison 10 speed

ACDelco TF928

Automatic transmission filter, internal

Allison 6 speed

GM 29542833

Transmission pan gasket

Allison 6 speed

GM 29549684

GM-Allison 10 speed

GM 24297922

Front differential gasket

2020 - 2021 models

GM 84756927 or GM 20768579

Rear differential gasket

2017 - 2019 models

GM 23445892

2020 - 2021 models

GM 84757352

6.6L Duramax L5P Oil & Fluid Specs, Capacities


Oil/Fluid Specification

Capacity [1]

Engine oil [2]

Ambient temp > 0° F

SAE 15W-40 API CJ-4 or CK-4
Recommend Amsoil Max Duty 15W-40 synthetic diesel oil

10 quarts w/ filter change

Ambient temp < 0° F
(acceptable in all temps)

SAE 5W-40 API CJ-4 or CK-4
Recommend Amsoil Max Duty 5W-40 synthetic diesel oil

Engine coolant

50/50 solution DEX-COOL engine coolant concentrate and distilled water
(GM DEX-COOL 12346290)

7.525 - 7.85 gallons

Automatic transmission fluid

Allison 6 speed

GM DEXRON VI automatic transmission fluid
(ACDelco 10-9243)

7.4 quarts service refill
12.7 quarts total capacity

GM-Allison 10 speed

GM DEXRON ULV automatic transmission fluid
(ACDelco 10-4107)

20.6 - 22.1 quarts total capacity

Transfer case fluid

2017 - 2019 models

GM DEXRON VI automatic transmission fluid
(ACDelco 10-9243)
Recommend Amsoil Signature Series FE synthetic ATF

1.6 quarts

2020+ models

2.4 quarts

Front differential fluid

SAE 75W-90 synthetic gear oil
Recommend Amsoil Severe Gear 75W-90 synthetic gear oil

1.8 quarts

Rear differential fluid

SAE 75W-90 synthetic gear oil
Recommend Amsoil Severe Gear 75W-90 synthetic gear oil

4.4 - 5.0 quarts

Diesel exhaust fluid

DEF meeting ISO 22241-1 specifications or equivalent, GM 19286291/ACDelco 10-4022

7.0 gallons

[1] Oil and fluid capacities are nominal; always fill to proper fluid indicator level (i.e. dipstick), fill plug height, or applicable level identifier. Vehicle should be parked on a level surface when checking or adjusting fluid level.
[2] 15W-40 engine oil preferred in ambient temperatures above 0° F. 5W-40 is acceptable in all ambient temperatures, but only preferred (and required) when ambient temperatures are below 0° F.