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Peterbilt 375 Transmission Filter Kit Guide for 1987-1996 Models

Keep your rig's transmission shifting smoothly by choosing the right filter kit for your specific setup.

4 minutes to read 1987-1996 Peterbilt 375
Difficulty
3/5
Est. Time
1.5 hrs
DIY Doable?
✅ Yes
Shop Labor
$150-$250
⚠️ Drivable, but... — You can drive to a repair shop, but you should address the issue immediately to prevent severe and costly transmission damage.
Key Takeaways
  • You must identify your specific transmission (e.g., Allison, Eaton) before purchasing a kit.
  • Symptoms of a bad filter include shifting problems, whining noises, and fluid leaks.
  • Wix is a reliable, high-quality aftermarket brand; inspect ATP gaskets for damage before installation.
  • Changing the filter is a critical maintenance task that prevents very expensive transmission failures.
The transmission filter kit is vital for the health of your Peterbilt 375's transmission. Its main job is to clean the transmission fluid. This fluid cools and lubricates the moving parts inside the transmission. The filter traps tiny metal shavings and other debris that can cause damage. For automatic transmissions, like an Allison, clean fluid is critical for the hydraulic pressure that controls shifting. For manual transmissions, like an Eaton Fuller, the filter keeps the gear oil clean to protect the gears and bearings from wear. A clean filter ensures proper fluid flow, preventing overheating and expensive repairs.

Before You Buy: Identify Your Transmission

The single most important step before ordering a transmission filter kit for your 1987-1996 Peterbilt 375 is to identify the exact transmission model in your truck. Peterbilt used different transmissions from various manufacturers during this period, most commonly automatics from Allison and manuals from Eaton Fuller. A filter kit for an Allison automatic is completely different from one for an Eaton manual.

Check the identification plate on the side of the transmission housing to get the manufacturer and model number. Ordering a kit based only on the truck's year and model will likely result in getting the wrong part.

Symptoms of a Clogged Transmission Filter

A failing filter can't clean the fluid properly, leading to problems. If you notice any of these signs, your filter may be clogged and need replacement.

  • Delayed or Hard Shifting (Automatics): If your automatic transmission hesitates to go into gear or shifts harshly, it could be due to low hydraulic pressure caused by a clogged filter.
  • Whining or Whirring Noises: A clogged filter can make the transmission pump work harder to circulate fluid, causing a distinct whining sound that changes with engine RPM.
  • Fluid Leaks: Increased pressure from a blockage can cause gaskets and seals to fail, leading to leaks.
  • Burnt Smell: Restricted fluid flow leads to overheating, which can burn the transmission fluid and create a burnt smell.
  • Visible Debris in Fluid: If you check your transmission fluid and it looks dark, murky, or has visible particles, the filter is likely saturated and not working correctly.

Check the Pan for Metal

When you drop the transmission pan to change the filter, inspect it and the magnet inside. A small amount of fine, gray dust is normal. However, if you find larger metal shavings or chunks, it's a sign of serious internal transmission damage that a new filter alone will not fix.

Choosing the Right Aftermarket Filter Kit

For the Peterbilt 375, you have options when it comes to aftermarket brands. Quality matters, as a failed filter can lead to a transmission replacement costing thousands of dollars.

Brand Tiers: Good vs. Better

  • Wix (Better): Wix is a well-respected name in the filter industry, known for making high-quality products for heavy-duty trucks. Their filters are built to meet or exceed OEM specifications, providing reliable filtration and durability. For peace of mind and long-term protection, Wix is a solid choice.

  • ATP (Good): ATP is a budget-friendly aftermarket option. They are known for their unique "3rd Hand" pan gaskets, which have special holes to hold the bolts in place during installation, making the job easier. However, there are reports of these fiber gaskets being folded and damaged in the box during packaging, which can cause leaks. While the filter itself may be adequate, inspect the gasket carefully before installation.

Pro Tip: Always Replace the Gasket

Even if a gasket looks reusable, it's best practice to replace it every time you drop the transmission pan. A new gasket ensures a proper seal and prevents leaks, saving you from having to do the job twice.

Aftermarket Transmission Filter Kit Cost for 1987-1996 Peterbilt 375

Part Type Price Range Notes
New Aftermarket Filter Kit $12.56 - $130.49 Price depends heavily on the transmission. Simple spin-on filters are at the low end, while complete kits for automatic transmissions (filter, pan gasket, O-rings) are at the high end.
New OEM Filter Kit (Allison) $90.00 - $110.00 Represents a genuine Allison kit, which often includes high-capacity filters and all necessary seals.

Frequently Asked Questions (FAQ)

Which transmission filter kit do I need for my Peterbilt 375?

You must get the model number directly from the identification plate on your transmission. The 1987-1996 Peterbilt 375 was equipped with different transmissions (like Allison or Eaton), and each requires a specific kit. There is no one-size-fits-all option.

Is a Wix filter better than an ATP filter?

Wix is generally considered a higher-quality and more reliable brand for heavy-duty applications. ATP is a budget option, but you should carefully inspect their gaskets upon arrival, as there have been complaints about them being damaged in the packaging.

What happens if I don't change my transmission filter?

Ignoring a clogged transmission filter will lead to poor transmission performance, overheating, and eventually, catastrophic failure. The cost of replacing a filter is tiny compared to the cost of rebuilding or replacing an entire transmission.

Can I change the transmission filter myself?

Yes, if you have mechanical experience, the right tools, and a safe way to get under your truck. The process involves draining hot fluid and dropping a heavy pan, so it is messy and requires care. You will need a large drain pan, sockets, a scraper for the old gasket, and a torque wrench.

Technical Specifications

OEM Part Numbers: 29548988 29540494 29558329 29548987

Kit contents vary by transmission. Automatic kits typically include filter(s), a pan gasket, and O-rings/seals. Manual transmission kits may be a single spin-on filter. Always verify the kit matches your transmission model number.

Wrenchy
Article researched & written by
Go-Parts' AI research assistant. Every article is backed by live web research, verified OEM data, and real technician knowledge — so you get accurate, up-to-date information you can trust.
Meet Wrenchy → Updated Jul 21, 2026

The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.

Year Coverage
This article covers the Transmission Filter Kit for:
  • Peterbilt 375: 1987198819891990199119921993199419951996
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