If you want a direct, heat-resistant replacement for Nissan and Infiniti cooling systems that fits tight without leaking, choose WZP 2PCS; if you need rugged durability for Jeep Wranglers, Cherokees, and older Chrysler vans with tough driving conditions, choose FALVFUN 2PCS.
• WZP 2PCS: The biggest strength is its precise engineering for Nissan/Infiniti models with high heat resistance to prevent deformation; the trade-off is it is strictly limited to that specific Japanese brand ecosystem. This pick is for owners of Altimas, Pathfinders, Maximas, and Infinitis looking for a seamless OEM-style swap.
• FALVFUN 2PCS: The standout feature is its robust ABS construction designed to withstand wear, scratches, and rough terrain common in Jeeps and older American vans; the trade-off is it does not fit the wide array of Asian luxury sedans. This pick is ideal for Wrangler TJ/WJ owners or anyone needing a cap that can handle heavy-duty abuse.
The WZP 2-piece set is engineered specifically for the cooling systems found in Nissan and Infiniti vehicles from the early 2000s through 2019. If you drive an Altima, Pathfinder, Maxima, or an Infiniti model like the G35, Q70, or JX35, this cap is built to replace your worn-out original part without requiring any modification. The design focuses on a perfect seal, utilizing specific outer and inner dimensions—1.5 × 1.5 inches on the outside and 1.2 × 1.2 inches on the inside—to ensure it locks tightly into place. This precision fitment is critical because a loose seal in these engines can lead to coolant loss and overheating, which are serious issues for modern performance cars.
What sets this product apart in my analysis is its material composition. Crafted from high-quality plastic with excellent heat resistance, it is designed to prevent cracking and deformation even under the intense thermal cycles of a running engine. When a coolant reservoir cap fails, it often cracks due to the constant pressure changes and high temperatures. The WZP unit addresses this by maintaining stable pressure within the system effectively. It serves as a direct replacement for multiple OEM part numbers, including 21712-79900 and 21712ZN50A, ensuring that the manufacturer's specifications for pressure retention are met. You get two black units in the package, which is practical for immediate replacement and having a spare ready in your glove box or tool kit for emergencies.
However, this product is not a universal solution. It will not work on a Jeep Wrangler or a Dodge Caravan because the mounting points and internal diameters differ significantly. If you own a Nissan or Infiniti, the value here lies in the exact fit and the ability to restore your cooling system to factory standards. If you try to force this into a vehicle it was not designed for, the seal will fail immediately. Therefore, this is strictly for those who have verified their specific vehicle year, model, and part number match the compatibility list before ordering. It is a targeted solution for a specific audience that needs reliability over versatility.
We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-11-06 · 7 min read · Independent comparison
The FALVFUN 2-piece cap is built for a completely different demographic: owners of older American and off-road vehicles. If you drive a Jeep Wrangler (TJ, WJ, XJ), Grand Cherokee, Liberty, Compass, Patriot, or various Chrysler minivans and sedans from the late 90s to the mid-2010s, this is the cap you need. The primary design goal here is toughness. Made from sturdy ABS material, the cap offers a robust structure that resists wear, scratches, and damage. This is particularly important for vehicles used in off-road conditions or harsh environments where debris might strike the engine bay components. The yellow color also makes it visually distinct, which can be helpful during maintenance checks to ensure you haven't lost track of the part or mixed it up with other components.
Functionally, this cap creates a fully enclosed space inside the tank to securely lock in the coolant. It replaces OEM numbers 52079331 and 55111074AA, providing a clear path for verification. The packaging options are flexible, offering single, double, or four-packs, which suggests the manufacturer understands that users of these older vehicles often need spares on hand for long road trips or DIY repairs. The dimensions of the unit are substantial, measuring roughly 2.2 x 4.7 x 2.2 inches, indicating a larger footprint than the compact WZP option. This size difference is not just cosmetic; it reflects the different engineering requirements of these older chassis and cooling systems.
The trade-off with FALVFUN is that it is not designed for the tighter tolerances of newer Japanese luxury cars. Its strength lies in its ability to handle the "rough and tumble" nature of the vehicles it supports. If you are driving a vintage Jeep or a family van that sees a lot of miles on bumpy roads, the scratch resistance and structural integrity of this ABS cap are valuable assets. However, if you need a cap for a 2018 Nissan Altima, this will simply not fit. It is a specialized tool for a specific class of vehicles that prioritize durability and longevity in the face of physical stress rather than the refined thermal management required by modern Japanese engineering.
• Best for Nissan and Infiniti Owners → WZP 2PCS: The fitment data aligns perfectly with Altima, Pathfinder, and Infiniti models, ensuring no leaks and proper pressure regulation.
• Best for Jeep and Chrysler Enthusiasts → FALVFUN 2PCS: The compatibility list covers Wranglers, Cherokees, and Minivans, making it the only logical choice for these specific platforms.
• Best Heat Resistance for Daily Driving → WZP 2PCS: The specific mention of high heat resistance and prevention of deformation makes it superior for keeping pressure stable in hot weather.
• Best Impact and Scratch Resistance → FALVFUN 2PCS: The ABS material is explicitly highlighted for resisting wear and damage, ideal for off-roading or rough parking lots.
• Best Compact Storage → WZP 2PCS: With a height of only 0.43 inches, it is incredibly thin and easy to stash in tight spaces like a glove compartment.
• Best Visual Distinction → FALVFUN 2PCS: The yellow color helps identify the part quickly during engine bay inspections compared to standard black caps.
• Best for Multiple Vehicle Maintenance → FALVFUN 2PCS: The availability of multi-pack options allows owners to stock up for entire fleets or frequent replacements.
• Best Direct OEM Replacement for Asian Brands → WZP 2PCS: It lists a wide range of specific part numbers for Nissan and Infiniti, confirming its role as a direct substitute.
After reviewing the specifications and intended use cases for both products, I would buy the WZP 2PCS if I owned a Nissan or Infiniti, because the precise fit and heat resistance are non-negotiable for preventing overheating in those specific engines. However, for my daily driver which happens to be a hybrid car, neither of these specific caps is the correct fit unless they match my vehicle's exact part number. In general, if you are torn between these two for a compatible vehicle, the WZP offers a more refined, compact solution for modern Japanese sedans, while the FALVFUN provides the heavy-duty protection needed for older American trucks and SUVs. I recommend choosing based entirely on your vehicle's make and model to avoid installation failures.
No, neither product is universal. WZP is designed exclusively for Nissan and Infiniti models, while FALVFUN targets Jeep, Chrysler, and Dodge vehicles. Always verify your OEM part number before purchasing.
The FALVFUN 2PCS appears more durable against physical abuse because it is made from sturdy ABS material designed to resist wear, scratches, and cracking, whereas WZP focuses on heat resistance.
Yes, both come in 2-piece packs. The WZP is particularly noted for its compact size (0.43 inches high), making it very easy to store in tight spaces like a glove box or tool kit.
The WZP 2PCS comes in black, which is standard for most engine bay components. The FALVFUN 2PCS is available in yellow, which can help distinguish it during maintenance or if you have multiple caps in the engine bay.
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