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If you own a Chrysler 300, the transmission cooler line is a small component that plays a big role in protecting the transmission from overheating and premature wear. Choosing the right cooler line can prevent leaks, maintain proper fluid temperature, and help avoid costly repairs down the road. This guide highlights seven shortlisted transmission cooler lines chosen for fit accuracy, durability, and leak resistance. Read on to understand the factors we considered and what to look for when selecting a replacement line.
Looking for other parts? See all Chrysler 300 parts & accessories.
Top Picks at a Glance
| Best Reviewed A top-rated pick with lots of positive feedback | GM Genuine Parts Transmission Cooler Lower Line |  |
| Most Popular A crowd favorite that many people choose with confidence | Autoutfit AN6 15ft Transmission Cooler Line Kit with Nylon Braided Hose |  |
| Best Quality Built to a higher standard if you want something more solid | A-Premium Automatic Transmission Oil Cooler Line Hose Assembly |  |
| Best Budget The cheapest option that still gets the job done reliably | LDCRE Quick-Connect Transmission Cooler Line Fittings, 2‑Piece |  |
| Most Sold A high-volume bestseller chosen again and again | EVIL ENERGY 6AN Braided Fuel/Transmission Line Kit, 15 ft |  |
| Best Value for Money The sweet spot between price and what you get | Generic Stainless Steel Braided AN6 Transmission Cooler Line Kit, 52-inch |  |
| Best Overall The best all-around choice for most situations | Generic 6AN 70" Stainless Steel Braided Transmission Cooler Line Kit |  |
1. GM Genuine Parts Transmission Cooler Lower Line
| Brand | GM GENUINE PARTS |
|---|---|
| Specific Uses For Product | Transmission Cooling |
| Manufacturer | ACDelco |
| Country of Origin | Canada |
This GM Genuine Parts lower transmission cooler line is a factory-quality replacement designed for transmission cooling systems. It installs in the vehicle’s transmission-to-radiator circuit and restores the original routing, fittings, and sealing surfaces so the cooling loop functions as intended. The metal construction and GM validation mean it matches factory fit and finish, which reduces the risk of leaks and overheating compared with an aged or damaged line. Typical use is direct replacement during a transmission service or when a leak or corrosion is found; several owners report tight fit tolerances that require patience and tools to maneuver clips and feed the line under the chassis. The product’s strong point is accurate fitment and durability, while the main practical limitation is that installation can be fiddly in confined areas and may require clip retrieval or creative access tools. Buyers should expect a repair-level part that restores factory performance but not an easier installation experience.
Best for: Reliability-focused buyers who prioritize restoring factory performance and longevity with a proven, brand-backed replacement part during a scheduled transmission service or leak repair.
Less Ideal for: Buyers seeking an easy, DIY-friendly swap with included hardware or a universal-fit aftermarket line that simplifies routing should look elsewhere.
- Factory-quality fit and finish validated for GM vehicles
- Metal construction suited to resist corrosion and lasting service life
- Matches original routing and connections to restore proper transmission cooling
- Backed by a recognizable automotive parts brand with long history
- Installation can be difficult in tight underbody spaces and may require special tools or clip retrieval
- Does not include retaining clips or accessories needed for some installations
Verdict Choose this GM Genuine Parts lower cooler line when you want a factory-matching, durable replacement to restore proper transmission cooling, but be prepared for a fiddly installation.
2. Autoutfit AN6 15ft Transmission Cooler Line Kit with Nylon Braided Hose
| Material | 304 Steel, Aluminum Alloy, Nylon, Rubber |
|---|---|
| Hose length | 15 Feet |
| Fitment note | Compatible with 4L60E 4L65E Transmission |
| Fitting type | -6 AN straight and 90° hose ends |
This Autoutfit kit supplies 15 feet of -6 AN braided transmission hose plus a selection of straight and 90° aluminum hose ends and transmission/radiator fittings to build or replace cooler lines. Intended for use with 4L60E/4L65E-equipped vehicles, the hose combines a rubber inner core with 304 steel wire reinforcement and a nylon outer braid for abrasion resistance while fittings are lightweight aluminum. In practice the kit is useful for custom routing and repairs where factory steel lines are corroded or too rigid, and the long length lets you trim to fit a Chrysler 300 with a 4L60E conversion or swap that accepts AN6 fittings. Installers should prepare for assembly: fittings require proper seating and some users add vice support or extra shop fittings for easier thread engagement. A few reviewers report the supplied radiator fitting does not thread as deeply on some factory radiators, so you may need additional adapters for a flush, OEM-style connection. The kit provides flexibility and modern hose construction but may need small parts or adapters to match Chrysler radiator ports exactly.
Best for: Convenience-driven buyers who want a ready-made hose-and-fitting kit to rebuild or custom-route transmission cooler lines quickly without fabricating parts from scratch.
Less Ideal for: Owners seeking a direct factory-style replacement that threads into Chrysler radiator ports without modification should consider a vehicle-specific OEM-style line or a kit that explicitly lists Chrysler 300 fitment and matching radiator adapters.
- Long 15 ft supply lets you cut custom lengths and tidy routing for engine bays
- Nylon-braided hose with steel wire reinforcement resists abrasion and holds pressure better than plain rubber
- Includes a mix of straight and 90° AN6 hose ends for flexible routing options
- Aluminum fittings are lightweight and corrosion resistant compared with steel alternatives
- Some radiator fittings in the kit have limited thread engagement on certain factory radiators, possibly requiring extra adapters
- Assembly needs care and hand strength; fitting installation can be difficult without a vise or proper tools
Verdict A flexible, long AN6 braided hose kit that simplifies building transmission cooler lines but may require extra radiator adapters for a flush Chrysler 300 installation.
3. A-Premium Automatic Transmission Oil Cooler Line Hose Assembly
| Brand | A-Premium |
|---|---|
| Manufacturer Part Number | APOCL187 |
| OEM Part Number | 5005204AA, 5005204AC, 5005204AD, 5005204AE, 5005204AF, 5005204AG, 5005205AA, 52014764AA, 624-284 |
| Item Weight | 1.03 pounds |
This A-Premium transmission oil cooler line hose assembly is a direct-replacement cooling line intended to restore proper fluid circulation between the transmission and its external cooler. It is used when factory lines leak, are corroded, or have failed fittings; installation involves swapping the old line for the new assembly and securing the factory-style connections. Notable features include multiple OEM reference numbers for fit verification, corrosion-resistant construction, and a one-year unlimited-mileage guarantee. For performance-oriented owners it delivers a straightforward way to eliminate leaks and regain reliable transmission cooling, which helps maintain shift quality and transmission temperatures under load. Some users report excellent fit and easy install, though a few mention that protective caps and clips may not match factory quality and might need to be reused or sourced separately. This is a practical, lower-cost replacement that restores function and cooling performance but may require small hardware swaps during installation to match factory assembly standards.
Best for: Performance-oriented buyers who prioritize restoring reliable transmission cooling to maintain shift quality and temperature control under towing or spirited driving.
Less Ideal for: Buyers seeking an exact factory-quality parts package including all original clips and caps or those unwilling to verify fitment before ordering should consider factory dealer parts instead.
- Direct-replacement design that restores transmission-to-cooler fluid flow
- Corrosion-resistant construction intended to resist leaks and deterioration
- Covers multiple OEM reference numbers for easier compatibility checks
- One-year unlimited-mileage guarantee provides short-term ownership protection
- May not include OEM-quality retaining clips or color-coded caps so extra hardware can be needed
- Not explicitly listed for Chrysler 300 fitment so vehicle compatibility must be verified before purchase
Verdict A practical, performance-minded replacement line that restores transmission cooling and stops leaks, but expect to confirm fitment and possibly reuse or source small clips separately.
4. LDCRE Quick-Connect Transmission Cooler Line Fittings, 2‑Piece
| Number of Pieces | 2 |
|---|---|
| Connector Type | Quick-Connect |
| Thread Type | NPT |
| Material Type | Stainless Steel |
These two quick-connect transmission cooler line fittings are intended as direct replacements for worn or leaking cooler line connectors on vehicles that use the listed factory part numbers. They install in the transmission cooler line circuit to restore a secure, leak-free connection and are typically used during transmission cooler line repair or when replacing a worn OEM connector. Notable features include quick-connect style engagement for faster installation and a metal-plus-rubber composite construction aimed at corrosion and heat resistance. In practice the fittings simplify repairs by eliminating the need for special tools and let you swap connectors quickly while working under the vehicle. Important limitations are that fitment is limited to vehicles using the exact OEM part numbers and the set contains only two fittings, so additional connectors or seals may be needed depending on the repair. These are a cost-conscious option for basic replacement rather than a heavy-duty performance upgrade.
Best for: Budget-conscious owners prioritizing a low-cost, straightforward replacement for Chrysler 300 transmission cooler line connectors who prefer a quick-install solution.
Less Ideal for: Those seeking a heavy-duty or upgraded aftermarket cooler line solution or anyone who needs a complete repair kit with multiple seals and clamps.
- Quick-connect design speeds up installation and reduces time under the vehicle.
- Metal and rubber composite construction resists corrosion and heat for longer service life than cheap plastics.
- Sold as a two-piece set to replace common twin fittings on transmission cooler lines.
- Direct-replacement for specific factory part numbers for straightforward compatibility when matched.
- Limited to vehicles that use the listed factory part numbers so fitment must be verified before purchase.
- Contains only two fittings and does not include additional seals or clamps that might be required for a full repair.
Verdict A budget-friendly, quick-connect OEM-style replacement for Chrysler 300 cooler line fittings when you need a fast, low-cost fix.
5. EVIL ENERGY 6AN Braided Fuel/Transmission Line Kit, 15 ft
| Material | Cpe Rubber inner with 304 steel wire and nylon braid |
|---|---|
| Hose Size (ID/OD) | 0.31" ID, 0.56" OD |
| Length | 15 Feet |
| Maximum Pressure | 750 Pound per Square Inch |
This EVIL ENERGY 6AN braided line kit supplies 15 feet of flexible AN6 hose plus a selection of swivel hose ends, adapters, clamps, and fittings intended for routing transmission cooler lines on a Chrysler 300. The hose uses a CPE rubber inner with a 304 steel wire layer and nylon braid, which gives it bendability for tight engine bays while retaining high working pressure (750 psi) for cooler and fluid circulation. Included swivel ends (straight and 90 degree) and adapters let you configure runs and connect to aftermarket cooler ports. In practice the kit is useful for custom cooler installs or replacing worn rubber lines when stock routing does not fit or when you want a tidy, stainless-braided appearance. Watch for fitment details because some buyers report missing or non-matching fittings for specific transmission ports, so plan to verify thread types on a Chrysler 300 beforehand and keep spare adapters on hand. The kit is a cost-effective, visually neat solution but requires basic plumbing familiarity for a leak-free install.
Best for: A risk-averse mainstream buyer who wants a reliable-looking, durable aftermarket line for a Chrysler 300 transmission cooler but prefers avoiding complex custom fabrication and values proven, commonly used components.
Less Ideal for: Not ideal for buyers who want a guaranteed bolt-on, vehicle-specific hose assembly that requires no measuring or adapter selection; those users should choose a Chrysler 300-specific kit or OEM-quality replacement.
- 15 feet of braided AN6 hose allows full custom routing for cooler installs
- High working pressure rating (750 psi) suitable for transmission cooler circulation
- Includes multiple swivel hose ends and adapters to configure straight and 90 degree connections
- Construction combines CPE inner, steel wire reinforcement and nylon braid for flexibility and abrasion resistance
- Fittings may not match every transmission port and some buyers reported missing or incompatible fittings
- Not a vehicle-specific kit so additional adapters or thread-matching may be required for a Chrysler 300
Verdict A flexible, high-pressure AN6 braided line kit that works well for custom transmission cooler runs on a Chrysler 300 if you confirm fittings and are prepared to source any adapter mismatches.
6. Generic Stainless Steel Braided AN6 Transmission Cooler Line Kit, 52-inch
| Material | Stainless Steel and PTFE |
|---|---|
| Length | 52 Inches |
| Fitting Size | AN6 |
| Compatible Transmissions | Turbo 350, Turbo 400, Turbo 200/200R4, Powerglide, 700R4, 4L60/4L60E/4L65E, 4L80E, Ford C4/C6/AOD |
This kit supplies stainless steel braided AN6 transmission lines and fittings to connect a Chrysler 300 transmission to an external cooler or to replace worn factory lines. Installation typically involves routing the pre-bent lines from the transmission outlets to a remote cooler, installing the included 90-degree fittings and transmission inserts where required, and sealing connections with appropriate tape or thread sealant. The braided PTFE core with stainless braid offers corrosion resistance, flexibility for routing behind the engine, and pressure-holding capability for towing or higher-load driving. Buyers benefit from longer, ready-made lengths and multiple adapter fittings that reduce custom hose-building. Limitations include the universal AN6 sizing which may not match the Chrysler 300 factory fittings without additional adapters, and mixed quality reports that indicate some kits arrive with inconsistent fittings or assembly issues, so expect to inspect and possibly chase threads before installation. For owners comfortable modifying fittings or sourcing an extra adapter kit, this is a cost-effective way to add transmission cooling capacity to a Chrysler 300.
Best for: Practical optimizers who want an affordable, do-it-yourself solution to add or replace transmission cooler lines on a Chrysler 300 and are willing to source one or two extra adapters if needed.
Less Ideal for: Drivers seeking a direct-fit, factory-quality replacement without any modification or extra parts should consider vehicle-specific hose assemblies from a dealer or specialist instead.
- Stainless steel braided PTFE construction resists corrosion and holds pressure.
- Includes 90-degree fittings and transmission inserts for common routing needs.
- Long pre-made hose lengths simplify adding a remote cooler without hose-building.
- Compatible with many automatic transmissions used in conversions when paired with the right adapters.
- Kit uses universal AN6 sizing that may require additional adapters to fit Chrysler 300 factory ports.
- Quality control appears inconsistent across units with occasional damaged or mis-sized parts.
- Some buyers report threads or fittings that need cleaning or chasing before installation.
Verdict A budget-friendly braided AN6 line kit that adds transmission cooling capacity to a Chrysler 300 if you are prepared to fit a small number of adapters and inspect parts before installing.
7. Generic 6AN 70" Stainless Steel Braided Transmission Cooler Line Kit
| Material | Stainless Steel/PTFE |
|---|---|
| Length | 70 Inches |
| Fitting size | 6AN |
| Included fittings | 90-degree adapters and transmission inserts |
This kit supplies two 70-inch stainless steel braided PTFE transmission lines with -6AN fittings plus assorted 90-degree adapters and transmission inserts to connect to a remote cooler. It is typically used to replace brittle factory hard lines or to add an auxiliary cooler for towing and spirited driving, moving fluid between the transmission and an aftermarket cooler to reduce operating temperature. The stainless braid and PTFE inner tube improve abrasion resistance and corrosion tolerance compared with rubber hose, and the included 90-degree fittings make routing easier in tight engine bays. Several buyers report the kit holds high pressure and installs cleanly when the factory fittings match -6AN sizing. Expect to source a few extra adapters on certain vehicles because the kit is marketed as universal and does not include every OEM-style quick-disconnect or ORB adapter. Quality control appears mixed in some batches, so inspect seals and threads before installation and have thread sealant or replacement fittings ready if needed.
Best for: Balanced owners who want a durable aftermarket transmission line kit to add a remote cooler or replace aging hard lines and who prioritize a mix of longevity and value.
Less Ideal for: Drivers seeking an exact fit, plug-and-play Chrysler-specific kit with OEM-style quick-disconnect fittings should consider a vehicle-specific assembly or professional hose shop instead.
- Stainless steel braid with PTFE core resists abrasion and corrosion for longer service life.
- 70-inch length covers many routing options and allows installation of a remote cooler.
- Includes 90-degree fittings and transmission inserts to simplify connections and routing.
- Holds high system pressure according to user reports, suitable for heavy use like towing.
- Universal fit means additional adapters may be required to match Chrysler-specific factory fittings.
- Some buyers reported inconsistent quality control including wrong lengths or damaged/used parts in rare cases.
Verdict A durable, value-oriented braided 6AN 70" kit good for adding a remote cooler to Chrysler 300s, but expect to source Chrysler-specific adapters or check fitment carefully before installation.
Choosing the Right Chrysler 300 Transmission Cooler Line: Key Factors to Consider
Fitment and Vehicle-Specific Compatibility
Correct fitment matters because a cooler line that does not match the Chrysler 300’s routing will be difficult to install, may rub against chassis components, and can lead to premature wear or failure.
Look for parts that reference exact model years, transmission type, and mounting points. A precise fit reduces the need for bending or modification during installation, which preserves line integrity and sealing surfaces.
Material and Corrosion Resistance
Materials influence how well a cooler line withstands road salt, moisture, and heat cycles. Hard lines are usually steel or aluminum with corrosion-resistant coatings, while hoses use synthetic rubber or reinforced polymer.
Choosing corrosion-resistant materials and protective coatings lengthens service life and lowers the chance of leaks developing from rust or material breakdown.
Sealing Method and Connection Quality
The type of fittings and seals determine how reliably the line holds pressure and resists fluid seepage. Common connection styles include flare fittings, crimped hose ends, and threaded adapters.
High-quality crimps, properly sized flares, and precision-machined mating surfaces reduce leak risk. Consider whether replacement includes new seals or O-rings, as reusing old seals can compromise the repair.
Routing and Bend Retention
How the line is routed affects clearance from heat sources and moving parts. Lines with good bend retention keep their shape after installation and resist kinking during vehicle movement.
A line that retains its bends and uses appropriate mounting clips will avoid contact with hot exhaust components, reducing thermal stress on the fluid and the line itself.
Durability Under Heat and Vibration
Transmission cooler lines operate near the engine and must handle continuous thermal cycling and drivetrain vibration. Hoses and fittings should be rated for high-temperature fluid, and hard lines should resist metal fatigue.
Reinforcement layers, braided coverings, or protective sleeves improve resistance to abrasion and vibration-induced fatigue, which helps prevent leaks and ruptures over time.
Installation Hardware and Support
Availability of correct fittings, clips, and mounting hardware simplifies installation and reduces install-time mistakes. Some kits include adapters and replacement clamps designed for the Chrysler 300’s layout.
Clear instructions and accessible technical support can be valuable if questions arise during installation, especially for first-time DIYers.
FAQ
How do I know if my Chrysler 300 transmission cooler line is leaking?
Common signs include visible fluid under the vehicle near the transmission area, a drop in transmission fluid level, or a strong smell of burning transmission fluid. You may also notice transmission slipping or erratic shifting if fluid loss becomes significant. Inspect lines and connections visually, and check fluid level regularly when you suspect a leak.
Can I replace a transmission cooler line myself?
Many owners can replace a cooler line with basic mechanical skills and the right tools, particularly if the new line is a direct-fit part. Ensure you have proper fittings, clamps, and an understanding of the vehicle’s routing. Take precautions to avoid contamination of the transmission system and follow torque specs for fittings. If routing or connection issues arise, professional help is advisable.
Should I choose a hard line or a hose for the cooler line?
Hard lines offer ruggedness and better resistance to abrasion and pressure, while hoses can provide flexibility where tight routing or engine movement is a concern. The best choice depends on the Chrysler 300’s original design and the specific routing needs. Prioritize materials and connections that minimize leak risk and suit the vehicle’s layout.
What causes transmission cooler line leaks besides corrosion?
Leaks can stem from loose or damaged fittings, degraded seals or O-rings, mechanical abrasion from contact with other components, and metal fatigue from repeated vibration. Incorrect installation or overtightening can also damage fittings. Regular inspection and correct routing help reduce these risks.
Do replacement cooler lines come with fittings and seals included?
Some replacement lines and kits include new fittings, clamps, and seals, while others supply only the line. Choosing a kit that provides the necessary hardware reduces the chance of mixing incompatible components and simplifies installation. Verify the contents before starting the job to ensure you have all required parts.
How We Chose the Best Chrysler 300 Transmission Cooler Line
We focused on factors that directly affect long-term performance and installation success for Chrysler 300 transmission cooler lines. Primary evaluation criteria included fitment precision to the vehicle chassis and transmission connections, material durability such as corrosion resistance and abrasion protection, sealing and connection design to minimize leaks, and ease of installation including supplied fittings and mounting hardware. We also considered the line routing and bend retention to ensure the part maintains shape under heat and vibration, plus warranty coverage and manufacturer technical documentation. Exclusions: we excluded products that lacked clear fitment validation for the Chrysler 300, components without specified materials or connection types, and items with inconsistent user feedback about leaks or premature failure. The chosen items met these filters and scored well on the measurable dimensions that matter for transmission cooling reliability.
Our full evaluation process is outlined in our review methodology.
Conclusion
When replacing a Chrysler 300 transmission cooler line, prioritize correct fitment, durable materials, and reliable connection methods. These factors have the biggest impact on leak prevention and long-term performance. Understand the routing and mounting needs, and prefer parts that include appropriate hardware or clear installation guidance. Balancing flexibility, corrosion resistance, and strong sealing will help you pick a solution that minimizes future service needs. If you are unsure about routing or sealing details, consult a technician who can confirm compatibility and installation technique to avoid common pitfalls such as abrasion or improper fittings.
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