Are OEM Serpentine Belts Better Than Aftermarket?

If you’re here, you might have a busted serpentine belt. You may also be wondering whether you should replace it with an OEM or an aftermarket belt.

The choice can be a difficult one. It can be hard to understand the difference between OEM and aftermarket serpentine belts. Both options are available to you, so it's best to know which choice is right for you.

Do you want to determine which type of serpentine belt offers the most value? Ask yourself the following questions:

1. Is The Serpentine Belt Designed To OEM Specs?

OEM serpentine belt

OEM serpentine belts offer the benefit of being exact replicas of the stock serpentine belt in your car. They’re built with the correct specifications. It's important for serpentine belts to fit correctly.

  • The serpentine belt has to be the right length
    • If it's too tight, it can't move and turn the pulleys well
    • If it's too loose, the components that are driven by the belt won't rotate at the correct speed.
  • The serpentine belt has to be the right width
    • If it's too thin, it can break off
    • If it's too thick, it can fall off

It's common for aftermarket serpentine belts to not come with the right dimensions. Aftermarket manufacturers design and build parts to their own specs. If you look on Amazon, you'll find reviews from Mazda owners. Plenty of them aren't happy with their aftermarket serpentine belts. Here are a few snippets:

  • "[My aftermarket serpentine belt] does not fit my Mazda 2.3L engine."
  • "I was not able to attempt to install [my aftermarket serpentine belt] until after my vacation. The belt was the wrong size. I was unable to return it."
  • "[This aftermarket serpentine belt] does not fit a MazdaSpeed3. It only goes from the crankshaft to the A/C. The MS3 needs a full serpentine belt."
  • "[This aftermarket serpentine belt] is not the right replacement item for the main belt. It's too short and not wide enough."

2. Does The Serpentine Belt Come With A Warranty?

OEM belt diagram

Even though serpentine belts are affordable, it's still important to get one that's warrantied. A warranty shows that the manufacturer stands behind its products.

Mazda offers a warranty on all parts sold by legitimate Mazda dealerships. The warranty is good for 12 months or 12K miles, whichever comes first. At, all our parts come with Mazda's warranty. It's because we're also a dealership. Know what's even better? You will only have to pay wholesale pricing on anything you order from us. That includes OEM serpentine belts. Sure beats driving to the nearest Mazda dealership and paying a markup of about 30% for the exact same part, doesn't it?

You would be hard-pressed to find an aftermarket serpentine belt that comes with a good warranty policy.

3. What Materials Are In The Serpentine Belt?

When it comes to serpentine belts, it's important to know which materials are used in them. As long as the engine is running, the serpentine belt keeps spinning and generating high temperatures. The materials in the belt have to withstand the heat and heavy use without breaking or changing the belt's shape/size.

Mazda makes its OEM serpentine belts with durable reinforced rubber that won't break or warp from heavy use. Since OEM serpentine belts are direct replacements, you won't get any surprises with the quality of the materials.

Aftermarket serpentine belts usually contain cheap materials that don't last long. For example, an Amazon reviewer wrote, "Do not buy [this aftermarket serpentine belt]. It shrank twice in the 90 days I had it. It also slipped off, so I pulled the belt tensioner bracket so hard that I stripped it. I had to buy a new belt and a new belt tensioner because I broke it trying to slip the belt over it. Very, very, very unsatisfied."

The Verdict: OEM Serpentine Belts Are Better

When it comes to serpentine belts (or any other auto part, for that matter), you get what you pay for. OEM serpentine belts are usually a little more expensive than aftermarket belts. They offer much more value in the long haul, though, because:

  • OEM serpentine belts always fit right
  • Aftermarket serpentine belts don't always fit right
  • OEM serpentine belts come with high-quality materials that can withstand high temperatures
  • Aftermarket manufacturers don't always build their serpentine belts with quality materials
  • All genuine OEM Mazda parts sold by a Mazda dealer are covered by a 12-month/12K-mile warranty
  • Aftermarket manufacturers rarely offer a warranty on their parts, including serpentine belts