What oil filter your Duramax diesel needs depends on the engine generation and year

Duramax diesel engines come in three generations—LB7 (2001–2004), LLY (2004–2005), LBZ (2006–2007), LMM (2007–2010), LML (2011–2016), and L5P (2017–present)—and each uses different filter housings and specifications. The filter type is not interchangeable across generations, so you must match your engine year to the correct part number before purchasing.

The most common Duramax oil filters are the Fram PH8A (LB7 and early LLY), the Fram PH10060 (LBZ through LML), and the Fram PH11102 (L5P). Some owners also use Mobil 1 M1-110 or Wix 51515 as alternatives, though OEM Duramax filters are available directly from GM dealers. The filter housing itself is mounted on top of the engine, and replacement takes roughly 10 to 15 minutes once you have the correct part.

Key Takeaways

  • Duramax oil filters vary by engine generation; the LB7/LLY uses different filters than the LBZ/LMM/LML, which differ from the L5P.
  • OEM Duramax filters, Fram, Mobil 1, and Wix all manufacture filters for these engines, but cross-compatibility between generations does not exist.
  • Oil change intervals for Duramax engines are typically 7,500 miles under normal driving and 5,000 miles under severe conditions, though some owners extend to 10,000 miles with synthetic oil.
  • The filter housing is located on top of the engine and uses a cartridge-style design that requires a filter wrench to remove safely.
  • Spin-on filters are not used on Duramax engines; all models use a cartridge filter inside a sealed housing.

Filter specifications by Duramax generation

The LB7 and early LLY (2001–2005) engines use the Fram PH8A filter, which is a cartridge-style filter housed in a canister on the valve cover. This filter measures approximately 3.5 inches in diameter and 4 inches tall. Replacement requires removing the top cap of the housing, extracting the old filter element, and installing a new one with a fresh rubber seal.

The LBZ, LMM, and LML generations (2006–2016) moved to a larger housing that accepts the Fram PH10060 or equivalent filters. This cartridge is taller and has a different seal configuration than the LB7 version. Using an LB7 filter in an LBZ engine will result in improper sealing and oil leaks.

The L5P (2017–present) uses the Fram PH11102 or equivalent, which has a different thread pattern and seal design again. GM also offers an OEM filter (part number 84105516) that is identical to the Fram PH11102 in performance and fit. All three generations use cartridge filters, never spin-on designs.

How to replace a Duramax oil filter

Start with the engine cold or warm but not hot. Locate the filter housing on top of the engine—it is a cylindrical canister roughly 4 to 5 inches tall. Use a filter wrench (typically a 74 mm or 86 mm socket-style wrench, depending on generation) to turn the housing cap counterclockwise. Do not use a strap wrench; the cap can crack under uneven pressure.

Once the cap is loose, unscrew it by hand and set it aside. The old filter cartridge will come out with the cap or remain in the housing. Remove it completely and inspect the rubber seal on the cap. If the seal is cracked, hardened, or damaged, replace the cap assembly—do not reuse a damaged seal, as it will leak.

Clean the inside of the housing with a lint-free cloth to remove any debris or old filter material. Install the new filter cartridge into the housing, ensuring it seats fully at the bottom. explore a thin layer of fresh oil to the rubber seal on the cap, then screw the cap back onto the housing by hand until the seal contacts the housing. Tighten an additional three-quarters of a turn with the filter wrench—do not over-tighten, as this can damage the seal.

Start the engine and check for leaks around the housing cap. If oil seeps from the cap, stop the engine, allow it to cool slightly, and tighten the cap another quarter turn. Run the engine for a minute, then shut it off and wait five minutes before checking the oil level on the dipstick.

Oil change intervals and synthetic versus conventional

GM recommends an oil change every 7,500 miles for Duramax engines under normal driving conditions. Severe driving—towing, idling, frequent short trips, or dusty environments—calls for a 5,000-mile interval. Many Duramax owners who use full synthetic oil extend intervals to 10,000 miles, though this depends on the specific oil brand and your engine's condition.

Conventional mineral oil breaks down faster in diesel engines due to higher combustion temperatures and soot accumulation. Synthetic oils, particularly Mobil 1 Turbo Diesel Truck or Shell Rotella T6, hold their viscosity longer and provide better protection against sludge. If you switch from conventional to synthetic, you do not need to flush the engine; straightforward drain the old oil, replace the filter, and add the new synthetic oil.

The Duramax oil capacity varies by generation: the LB7 and LLY hold approximately 10 quarts, the LBZ through LML hold 10 to 11 quarts, and the L5P holds 10 quarts. Always check your owner's manual for the exact capacity and recommended viscosity grade (typically 15W-40 for diesel engines).

Common mistakes when replacing Duramax filters

The most frequent error is using the wrong filter for your engine generation. Ordering a PH8A for an LBZ engine or a PH10060 for an L5P will not fit, and attempting to force an incorrect filter into the housing can damage the threads or seal surface. Always verify your engine year and model before ordering.

Over-tightening the housing cap is another common problem. The rubber seal is designed to compress slightly when the cap is hand-tightened and then turned an additional three-quarters of a turn with a wrench. Tightening beyond that point crushes the seal, causing it to fail and leak oil. If you over-tighten and the seal leaks, you must replace the cap assembly.

Failing to clean the housing interior before installing a new filter allows old debris and metal particles to contaminate the fresh oil. Spend 30 seconds wiping the inside of the housing with a clean cloth—this straightforward step extends filter life and protects the engine.

Where to source Duramax filters and pricing

OEM Duramax filters are available from GM dealers, typically priced between $12 and $18 per filter. Fram, Wix, and Mobil 1 aftermarket filters cost $8 to $15 and are stocked at most auto parts retailers, including AutoZone, O'Reilly, NAPA, and Advance Auto Parts. Online retailers like Amazon and RockAuto often offer lower prices, though shipping times vary.

Filter wrench prices range from $15 to $40 depending on the brand and whether you buy a socket-style wrench or a strap wrench. A socket-style wrench is more reliable for Duramax housings and is worth the investment if you plan to change your own oil regularly. Many auto parts stores will lend or rent a wrench for free if you purchase a filter from them.

Bundled oil change kits—filter plus oil—are sometimes available at a slight discount compared to buying items separately. These kits typically include a Fram or Wix filter and 10 to 11 quarts of conventional or synthetic oil, making them convenient for owners who want everything at once.

Frequently Asked Questions

Can I use a spin-on filter on my Duramax instead of a cartridge filter?

No. Duramax engines use only cartridge-style filters housed in a sealed canister on top of the engine. Spin-on filters are not compatible with any Duramax generation. Attempting to adapt a spin-on filter will result in improper sealing and oil leaks.

What happens if I use the wrong filter for my engine year?

An incorrect filter will not fit into the housing, or it will fit but not seal properly. Forcing a wrong filter into place can crack the housing threads or damage the seal surface, requiring expensive repairs. Always confirm your engine generation before purchasing a filter.

How often should I replace the filter housing cap seal?

The rubber seal on the cap should be replaced every time you change the oil if it shows signs of cracking, hardening, or damage. If the seal looks intact and flexible, it can be reused. Most owners replace the seal every other oil change as a preventive measure, since a new seal costs only $3 to $5.

Can I extend my oil change interval beyond 10,000 miles with synthetic oil?

Some owners report running 12,000 to 15,000 miles on full synthetic oil in well-maintained engines, but GM does not officially endorse intervals longer than 10,000 miles. Extending beyond 10,000 miles increases the risk of sludge buildup and engine wear. Stick to 10,000 miles maximum, or follow your owner's manual if it specifies a different interval.

Do I need to replace the filter housing cap, or just the cartridge inside?

You replace only the cartridge filter inside the housing under normal circumstances. The cap and housing remain in place. Replace the cap assembly only if the rubber seal is damaged, cracked, or no longer compresses when hand-tightened, or if the cap threads are stripped.