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3.0 Duramax Maintenance: Intervals and Fluids

Updated: May 10

Owners manuals are going away but a quick overview of everything you need to know if you are doing your own maintenance is right here –Fuel Filter / Engine Oil / Differential Fluid / Transfercase Fluid / Transmission Fluid

Everyone should be able to maintain their own vehicles if they wanted and this guide will hopefully assist you in doing so. If you are one who prefers to have it done elsewhere, this guide could also be helpful in overall knowledge of what is included in certain services. As of this articles writing, everything has been verified to be correct, however, it is to be noted that anything can change and it is your responsibility to verify correct fluids and capacities with your local dealer using your vin number. Information shared is that of my own personal vehicle on the maintenance it requires and solely my opinion with addition of some variables.

If doing your own maintenance, it is important to maintain a record of all parts receipts and list the mileage and the date of any service work performed. It can be dangerous to work on your own vehicle if you do not have proper knowledge, service manual, tools, or parts. Always follow owners manual procedures and consult the service manual for your vehicle before doing any work. Information provided is meant to be vague with an assumption of basic automotive knowledge and is meant for entertainment purposes. / DemonWorks LLC cannot be held liable for anything you do after reading this as it is not meant to be a how-to guide and any actions you perform are that of your own. Affiliate Links provided may provide us some monetary compensation but will not effect the price on your end.

Maintenance Intervals

Engine Oil + Tire Rotation - 7500 Miles / 12 Months / Follow Oil Life Monitor

Passenger Compartment Air Filter - 24 Months

Fuel Filter - 30,000 Miles / 24 Months / Follow Fuel Filter Life Monitor

Engine Air Filter - 45,000 Miles / Follow Engine Air Life Monitor

Transmission Fluid + Filter (SEVERE USE) - 45,000 Miles

Transfer Case Fluid (SEVERE USE) - 50,000 Miles

Front Differential Fluid* (SEVERE USE) - 50,000 Miles

Rear Differential Fluid* (SEVERE USE) - 50,000 Miles

Brake Fluid - 60 Months

Transfer Case Fluid - 100,000 Miles / 10 Years

Front Differential Fluid* - 100,000 Miles / 10 Years

Rear Differential Fluid* - 100,000 Miles / 10 Years

Cooling System Drain and Fill - 150,000 Miles / 72 Months

Oil Pump Belt 2020-2022 Models 150,000 Miles / 180 Months

Oil Pump Belt 2023+ Models 200,000 Miles / 180 Months

* Denotes Item Not listed in Owners Manual / Other resources. Suggestion made in place.


Engine Oil (7500 miles / 12 Months / Follow Oil Life Monitor)

Drain plug located at base of engine oil pan (15mm). Oil Filter Located on right side of engine oil pan. You will need 7 Quarts of engine oil and Dexos D Oil 0w20 is required. ACDelco Oil Filter is suggested but other aftermarket options are available as well. To check the engine oil, it is suggested to get the vehicle up to temperature then allow to sit for at least 15 minutes before checking the dipstick.

ACDelco Oil Filter:

PPE Oil Filter:

ACDelco Engine Oil:


Passenger Compartment Air Filter (24 Months)

Passenger compartment air filter, also referred to as Cabin Air Filter, is located behind the glove box on the passenger side.

ACDelco Cabin Air Filter:

Fuel Filter (30,000 Miles / 24 Months / Follow Fuel Filter Life Monitor)

The Fuel Filter is a critical part of the fuel system and while this interval is 30,000 Miles, it is my opinion that one should change the filter sooner. The filters are fairly cheap and the procedure to replace it is relatively easy.

The Fuel Filter housing is located on the left side frame rail and a 36mm Socket on a ratchet is required for removal. The new fuel filter comes with replacement o-rings and both must be replaced. 18ft lbs is all that is needed to snug the cap properly. Be sure to prime the system after replacement and verify no leaks at the housing. Priming is done by holding the "start" button on your vehicle WITHOUT your foot on the brake. You will hear the pump kick on and fill the housing. Reset your Fuel Filter Life at this time.

ACDELCO Fuel Filter:

36mm Socket (3/8" Drive):

GearWrench Ratchets:

Engine Air Filter (30,000 Miles / 24 Months / Follow Air Filter Life Monitor)

Engine air filter is easily accessed in the engine bay. The airbox lid is held on with 3 8mm bolts and an air box boot.

ACDelco Air Filter:

AIRAID filter (Non-Oiled)

Transmission Fluid + Filter (SEVERE USE 45,000 Miles) (90,000 Miles)

Severe use is for people using their vehicle to tow, high RPM, aggressive driving or a lot of stop and go traffic. The transmission fluid requires some special tooling to fill and can be a messy job. There is no drain plug so when removing the 10mm bolts holding the pan on, it will spill out and requires some careful planning ahead of time. If you have a tool that can suck the fluid out, you can do so with the pan lowered at an angle. The transmission pan gasket is reusable. The filter bolts are one time use only and require a "kit" during replacement of the transmission filter. Filter bolts are torqued to 44 in/lb then 128 degrees. The transmission pan bolts are torqued to 93in/lb and need to be tightened in a sequence. To fill, a tool is required to pump the fluid in to the left side of the transmission through the access plug. The transmission fluid temperature must be 167 - 176 degrees when checking to have the proper level. Level is checked by removing the side plug and the fluid should have a steady flow that turns into a drip, at this point, the fluid level is correct.

Fluid level check with Pan cleaned and in place.

- fill through side plug roughly 8.1 quarts then install side plug

- run vehicle until up to 167-176f degrees (shift to "Drive" "Neutral" "Reverse")

- remove side plug (CAUTION-VERY HOT)

- fill if no fluid is coming out

- let drain until fluid drips out

- install plug with blue loctite

Transmission Filter Bolt Kit -

Dexron ULV (said to be certified)(have not tried) -

Transfer Case - (SEVERE USE 50,000 Miles) (100,000 Miles)

The transfercase is easily serviced by way of a drain plug on the bottom. Just a standard 3/8" ratchet will be able to remove and reinstall. The fill plug is located just above and is the same 3/8". Fluid required to service is 1.6 Quarts of Dexron VI. *NOTE- a pump is suggested to put fluid in, the fluid bottles are available in 2 sizes and I will not recommend a screw on pump due to the variations. Linked a regular style pump, however.

Dexron VI Fluid -

Tool to fill :

Rear Differential - (SEVERE USE 50,000 Miles)(100,000 Miles)

The rear differential service interval is not found anywhere in my research for the 2020+ 3.0 equipped vehicles. For this recommendation I am going to follow the transfer case interval as I feel that is an appropriate time to take care of the drivetrain fluids. There are multiple options that could be on your vehicle and this is where you will need to look up your RPO codes to see what your vehicle is equipped with. The fluid and capacity will vary with each.

The service is simple, removal of the rear cover is required then clean the reusable gasket and cover then reinstall. Fill the differential at the side fill plug that just needs a 3/8" ratchet to remove and reinstall. Fill until it is just below the plug. Many will fill until it drips out of the plug and while that is not the recommended level, they seem to do just fine.

9.5" SU7 2.59 Quarts :

9.76" G80 2.75 Quarts :

9.76" G94 2.75 Quarts :

Tool to fill :

Front Differential - (SEVERE USE 50,000 Miles) (100,000 Miles)

The front differential service interval is not found anywhere in my research for the 2020+ 3.0 equipped vehicles. For this recommendation I am going to follow the transfer case interval as I feel that is an appropriate time to take care of the drivetrain fluids. There are multiple options that could be on your vehicle and this is where you will need to look up your RPO codes to see what your vehicle is equipped with. The fluid and capacity will vary with each.

The Process to do this service is much more involved than the rear differential as the area is very tight. I highly suggest you watch the video. The front cover must be removed and the gasket is a 1 time use so be sure to have one on hand. The fill port is tough to access and I suggest a filler tool to complete the task. Fill until the fluid comes out then remove a small amount.

8.0" G93 1.16 Quarts

8.0" SU4 1.16 Quarts :

Brake Fluid (60 Months)

Brake fluid is suggested to be replaced at 5 years / 60 Months. Due to the safety implications of improperly performing a swap of fluid, I will not suggest fluids or how to do the procedure. Just know, it is to be serviced at 5 years / 60 Months.

Cooling System (150,000 Miles / 60 Months)

Cooling system drain and fill sounds easy but it's not as easy as one may think. There is a drain at the radiator but there will still be coolant throughout the system that you cannot access. In addition, the fill procedure requires the use of a 50/50 dexcool / distilled water mixture by way of a "Vac-n-fill" tool.

Oil Pump Belt (150,000 Miles 2020-2022) (200,000 Miles 2023+) (15 Years / 180 Months)

The 3.0 Duramax Diesel is equipped with an wet belt that operates within the engine oil and is used to operate the mechanical oil pump. Often hated by many due to the design and the maintenance interval. The time changed for the 2023 vehicles but what appears to be no change in the belt part number. It is rumored that the engineers found the belt to outperform expectations and extended the service interval.

The belt is located at the rear of the engine and requires the transmission to be removed where one can then access the lower rear cover plate that houses the rear main seal. The belt does not have a tensioner or any special timing procedure and is then easily swapped. Take a look at the video to see what it looks like.

There have been many people commenting on the youtube videos and forums about outrageous quotes but the job doesn't cost as much as many seem to think. The labor based off AllData time is currently showing 9.3 Hours but average quotes I have seen are 12-14 hours. The parts costs could vary by shop and location but a likely around $500 or less.

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