6.6L Duramax LMM Maintenance Schedule (Service Intervals)
"Severe duty" service conditions may include any of the following:
• Light towing that exceeds 1,000 miles during any applicable service interval.
• Medium to heavy towing or hauling payloads that place the vehicle near its maximum GVWR.
• Extended periods of idling, generally accepted as 10 minutes of idling or more during a 60 minute window.
• Driving off-road or in dusty conditions.
• Frequent driving in heavy stop-and-go traffic conditions.
• Driving in a manner that prevents the engine from reaching normal operating temperature (frequent stops and/or short trips).
| Description | Service Interval(s) | Notes/Remarks |
| Replace engine oil & oil filter | 10,000 miles/12 months or when "change engine oil" message is displayed by the oil life monitoring system | [1] |
| Replace fuel filter, drain water separator | 15,000 miles | --- |
| Replace engine air filter | 45,000 miles | [2] |
| Perform engine cooling system service | 150,000 miles | [3] |
| Replace automatic transmission fluid & filters | 50,000 miles under normal conditions 25,000 miles under severe duty conditions |
[4] |
| Replace transfer case fluid | 50,000 miles | [5] |
| Replace front differential fluid | 50,000 miles | [5], [6] |
| Replace rear differential fluid | ||
| Perform multi-point inspection | At oil change intervals | [7] |
[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] Replace external and internal transmission filters, replenish with new automatic transmission fluid.
[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 LMM Service Parts List
| Part Description | Part Number | |
| Engine air filter | ACDelco A3087C | |
| Engine oil filter | ACDelco PF2232 | |
| Oil pan drain plug | GM 11569943 | |
| Oil fill cap | GM 97350955 | |
| Fuel filter | ACDelco TP3018 | |
| Serpentine belt | ACDelco 6K1195, Gates K061195 | |
| Thermostat | Front | ACDelco 12T100D |
| Rear | ACDelco 12T99D | |
| Thermostat housing gasket | ACDelco 97223686 | |
| Coolant reservoir cap | ACDelco RC85 | |
| Upper radiator hose | 2007 - 2008 | ACDelco 24589L, Gates 23227 |
| 2009 - 2010 | ACDelco 24655L, Gates 23499 | |
| Lower radiator hose | ACDelco 26570X, Gates 23260 | |
| Glow plug | ACDelco 9G (replaces ACDelco 61G) | |
| Automatic transmission filter, auxiliary (external) | ACDelco TF950, Allison 29539579 | |
| Automatic transmission filter, internal | ACDelco TF920 | |
| Transmission pan gasket | ACDelco 29549684 | |
| Front differential gasket | N/A | |
| Rear differential gasket | 14 bolt, GM 10.5 | GM 26067159 |
| 14 bolt, AAM 11.5 | GM 12471447 | |
6.6L Duramax LMM Oil & Fluid Specs, Capacities
| Item | 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) |
6.15 - 6.35 gallons | |
| Automatic transmission fluid | GM DEXRON VI automatic transmission fluid (ACDelco 10-9243) |
7.4 quarts service refill 12.7 quarts total capacity |
|
| Manual transmission fluid | N/A - manual transmission not available | ||
| Transfer case fluid | GM DEXRON VI automatic transmission fluid (ACDelco 10-9243) Recommend Amsoil Signature Series FE synthetic ATF |
1.6 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 | 14 bolt GM 10.5 | SAE 75W-90 synthetic gear oil Recommend Amsoil Severe Gear 75W-90 synthetic gear oil |
3.2 - 3.5 quarts |
| 14 bolt AAM 11.5 | 4.4 - 5.0 quarts | ||
[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.