Are OEM Duramax Fuel Filters Better Than Aftermarket?

When you need a new fuel filter for your Duramax 6.6L, you might be tempted to think any old filter will do. However, just like all of the other parts you may buy for your Silverado or Sierra HD, it’s important to remember that quality is the most important factor. An OEM fuel filter is a significant upgrade over cheap aftermarket units.

First, Are We Talking Filters or Filter Housings?

Filter parts

Right off the bat, we need to differentiate between a fuel filter and the whole fuel filter housing:

  • The filter itself is part number 12664429, which you can find here
  • The filter housing assembly (which includes the filter, filter head, and water in fuel sensor), is part number 12642623, which you can find here

Most of the time, you're going to want the filter only (part #12664429). However, because it's a good idea to replace the filter every 10-15k miles, the head and the sensor can get loose and start to leak a bit. When they do, it's a good idea to buy the entire filter housing assembly.

Why OEM Quality Is So Important

Aftermarket fuel filters are generic. This is because generic filters - which use generic filter media and a generic design - are cheap. Unfortunately, generic filters don't perform as well as you'd like:

  • Generic filter media can quickly clog, especially if it's not specifically designed for diesel engines (and again, most of the aftermarket filters are generic)
  • Once a filter becomes clogged, it's no longer a will instead become an obstacle in your fuel system, which can lead to rough engine starts and drivability problems
  • More importantly, when a filter is clogged and no longer filtering, contaminants pass thru your fuel injectors

In no time at all, a cheap fuel filter can damage your injectors. Considering a set of OEM fuel injectors cost thousands of dollars to replace (they're about $300 each), any "savings" you might enjoy on an aftermarket filter will be lost if you have to replace even one injector.

OEM fuel filters, on the other hand, have filter media designed for the specific application. They're also easier to install (better part tolerances), less likely to leak, and backed by a GM warranty.

Three Things To Think About When Buying A Fuel Filter Housing

Filter location

Image Credit: DieselWorldMag

Let's talk about the 3 most important factors in choosing a replacement fuel filter housing. All these factors ensure a high quality part that performs well and will save you money in the long run.

1. Design And Fitment

Fuel filter housings are one of those parts that need excellent workmanship to function right. A Duramax diesel fuel filter housing has three different components:

  1. Fuel filter head
  2. Water in fuel sensor
  3. The fuel filter (also sometimes called a filter housing)

For the entire unit to function, all the components need to fit precisely together, and function perfectly together. That means each component needs to be designed to OE specs. Many aftermarket manufacturers use their own designs for their fuel filter housings. Many of them will claim that their designs are superior to the OE design. But there's no way for you to tell if their claims are true unless you test the part yourself.

Since the fuel filter housing is an important part, it's a good idea to get a replacement unit that's designed to OE specs. The only way to be sure that you'll get a replacement housing that fits perfectly is to order an OEM component.

2. Material Quality

GM doesn’t cut corners on its OEM parts. That includes fuel filter housings. GM makes a point to only use high quality materials. It makes sure that its fuel filter housings perform as expected for their lifetime.

It’s pretty common for aftermarket manufacturers to sneak some inferior quality materials into their parts. For that reason, it's pretty common for aftermarket fuel filter housings to cause problems due to:

  • Using low quality o-ring seals: Cheap o-ring seals can crack and let air enter the fuel system
  • Cracks in the filter housing: Low quality materials are more prone to cracking

3. Warranty

GM offers a limited lifetime warranty on its OEM parts. It means that they will replace your fuel filter housing for free if it has a manufacturing defect.

You may be hard-pressed to find an aftermarket fuel filter housing that comes with a comprehensive warranty. If your aftermarket fuel filter housing leaks or develops a crack, chances are you would have to pay out of pocket for another one.

Summing Up

When you buy an OEM fuel filter or fuel filter housing online, it's usually only a few dollars more than a cheap aftermarket part. However, it's guaranteed to fit, perform, and protect your engine. Considering how small the price difference is between OEM and aftermarket, and considering how vital the fuel filter or housing is to engine performance and injector performance, it only makes sense to buy OEM.