The VQ35DE engine in the 350Z is notorious for eating its original plastic valve covers, leading to oil leaks, misfires, and that unmistakable burning smell. Moving to a well-designed aluminum cover is one of the smartest preventative maintenance steps you can take, but the aftermarket is flooded with options ranging from cheap castings to high-end billet pieces.
I’m Amir — the founder and writer behind Four Wheel Ask. I’ve spent years parsing through technical data sheets, comparing material hardness ratings, gasket crush specifications, and correlating them with long-term owner feedback to separate genuine upgrades from flashy parts that fail within months.
This guide focuses strictly on build quality, gasket sealing surface design, PCV integration, and real-world durability reports to help you select the best 350Z valve cover that provides a permanent fix for your engine’s oiling system.
How To Choose The Best 350Z Valve Cover
Selecting the right valve cover involves more than just picking a color. The wrong choice can lead to vacuum leaks, oil consumption, or even damage to your ignition system. Here are the critical factors to evaluate before buying.
Material Selection: Plastic vs. Aluminum
The factory plastic covers warp over time due to heat cycles, breaking the seal at the spark plug tubes and the perimeter gasket. Aluminum covers dissipate heat better and provide a rigid mounting surface that resists warping, making them the clear long-term upgrade.
Gasket and Seal Quality
Many budget kits include gaskets that are too stiff or too soft, leading to immediate leaks. Look for kits where the gasket material matches the crush characteristics of the factory Nissan part. Replaceable spark plug tube seals are a major plus, as they allow future servicing without replacing the entire cover.
Included Components and Hardware
The best kits include everything: covers, gaskets, bolts, PCV valve, oil filler cap, and spark plug tube seals. However, the quality of these included parts varies widely. High-quality bolts and a properly baffled PCV system are essential for preventing oil from being sucked into the intake manifold.
Quick Comparison
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| Model | Category | Best For | Key Spec | Amazon |
|---|---|---|---|---|
| MITZONE Red Aluminum | Valve Cover (350Z) | Best Overall | VQ35DE, Full Kit, Red | Amazon |
| MILIPARTS Silver Aluminum | Valve Cover (350Z) | Premium Value | VQ35DE, Silver, PCV incl. | Amazon |
| CNS Valve Cover Kit | Valve Cover (350Z) | Complete Kit | VQ35DE, w/ Coils & Gaskets | Amazon |
| MILIPARTS Metallic Set | Valve Cover (350Z) | Durable Build | VQ35DE, Metallic Paint | Amazon |
| A-Premium Pair | Valve Cover (Nissan) | Budget Truck/SUV | VQ40DE, Plastic, 2pc | Amazon |
| Tuningsworld Aluminum | Valve Cover (Chevy) | Classic Muscle | SBC 283-400, Billet Rail | Amazon |
| Alum. Finned Tall Covers | Valve Cover (Chevy) | Roller Rockers | SBC 305-350, Center Bolt | Amazon |
| Billet Specialties | Valve Cover (Chevy) | Hot Rod Style | SBC, Polished, Chevy Logo | Amazon |
| Cuztom Tuning Mirror | Exterior (350Z) | Exterior Style | Z33, Real CF, 2pc | Amazon |
| MCARCAR Mirror Caps | Exterior (350Z) | Exterior Style | Z33, Real CF, UV Protected | Amazon |
| Generic Interior Carbon | Interior (350Z) | Cabin Style | 06-09 Z33, 5pc Center | Amazon |
In‑Depth Reviews
1. MITZONE Upgrade Aluminum Valve Cover
The MITZONE red aluminum covers represent the ideal balance of style, durability, and completeness for the VQ35DE. Designed specifically for the 2003-2008 350Z and compatible Infiniti models, these covers ditch the problematic plastic design in favor of a rigid aluminum frame that resists the thermal warping common to the factory units. The kit arrives pre-assembled with bolts, oil cap, gaskets, plug tube seals, PCV valve, and even a new hose.
Owner feedback consistently highlights the “perfect fitment” and the fact that the kit includes everything needed for a weekend swap. The red powder coat provides a distinct visual upgrade under the hood, though multiple users note the paint is not overly durable and can scratch during installation if care is not taken. The included gaskets are serviceable, but several experienced builders recommend pairing these covers with OEM Nissan gaskets for maximum leak prevention.
One common point mentioned in longer-term reviews is that the threaded holes for the coil packs are slightly shallow. This requires using the provided shorter bolts or adding washers to prevent the coils from seating improperly. Overall, it is the most complete and confidence-inspiring package for a 350Z owner looking to permanently solve oil leaks.
What works
- Truly complete kit with all necessary hardware
- Rigid aluminum construction prevents future warping
- Replaceable spark plug tube seals add long-term value
- Excellent fitment reported for the VQ35DE
What doesn’t
- Paint finish can scratch easily during handling
- Included gaskets are stiff; OEM gaskets recommended for best seal
- Coil pack bolt holes may require washers for proper depth
2. MILIPARTS Upgrade Aluminum Engine Valve Cover Set
MILIPARTS offers a strong contender for the 350Z community with their silver aluminum cover set. Like the MITZONE kit, this is a direct replacement for the VQ35DE found in the 350Z, FX35, G35, and M35. The metallic paint finish gets specific praise in owner reviews for its “glitter in the sun” appearance, offering a factory-plus look that doesn’t scream aftermarket.
The kit includes the valve covers, oil filler cap, gaskets, bolts, spark plug tube seals, PCV valve, and a PCV hose. A major selling point is the replaceable tube seals, which contrasts with the factory Nissan units where the seals are integrated into the plastic cover, forcing a full replacement if they leak. Owners recommend taking the time to clean up minor casting flash around the baffle area before installation to ensure optimal PCV function.
A recurring theme in the feedback is that while the included gaskets work, the community consensus leans towards using OEM gaskets for the absolute best seal. Additionally, some users found that one or two of the provided bolts were slightly too long and required swapping for a shorter hex-head screw to prevent bottoming out or stripping the threads in the head. For the price, it represents an excellent upgrade from the factory plastic units.
What works
- Excellent metallic finish looks great under the hood
- Complete set including PCV valve and tube seals
- Replaceable tube seals are a major upgrade over OEM
- Significant cost savings compared to dealer parts
What doesn’t
- Minor casting cleanup needed around baffle area
- Included gaskets not considered top-tier by owners
- One or two bolts in the kit may be slightly too long
3. CNS Valve Covers with Gaskets and Ignition Coils
The CNS kit takes a different approach by bundling the valve covers with a full set of six ignition coils, making it a compelling option if you are tackling a misfire issue alongside an oil leak. The valve covers themselves are reported to be “sturdy built” and fit the VQ35DE engine perfectly, matching the specifications for the 2002-2009 Nissan and Infiniti 3.5L models.
However, this kit comes with a significant caveat that is well-documented in the customer review section. While the valve covers and gaskets function as intended, the included ignition coils are widely reported to be of dangerously low quality. Multiple owners describe immediate engine stumbling, check engine lights, and in one severe case, a coil that “exploded with loud bang, smoke” potentially destroying the ECM.
The consensus among buyers is that this kit offers excellent value strictly for the valve covers, gaskets, and tube seals. The consensus strategy is to purchase this kit for the core components and immediately discard or replace the ignition coils with a reputable brand like Hitachi or Denso to avoid catastrophic engine electrical damage. If you need coils, this can be a bargain, but factor in the cost of replacing them from the start.
What works
- Valve covers and gaskets fit the VQ35DE very well
- Comes with all 6 ignition coils for a full tune-up
- Sturdy build quality on the metal covers
- Excellent value if you only need the core parts
What doesn’t
- Included ignition coils are unreliable and potentially dangerous
- Coils can cause misfires and ECM damage
- Essentially requires buying separate quality coils
4. MILIPARTS Valve Cover Set Left and Right
This earlier MILIPARTS offering provides essentially the same core hardware as their silver set but at a slightly lower entry point. It covers the same wide range of vehicles, including the 2003-2008 Nissan 350Z and Infiniti G35, FX35, and M35 with the 3.5L V6. The metallic paint finish gets high marks, with owners noting it “really glitters in the sun” and provides a perfect match for the modern engine bay aesthetics.
The kit includes the left and right valve covers, plug tube seals, PCV valve, gasket, bolts, cap, and tube. One specific advantage highlighted by a long-term user is that the tube seals are replaceable, unlike the OEM Nissan covers. This feature alone can save significant money down the line when the seals inevitably harden and begin to leak oil into the spark plug wells, as it avoids buying entirely new covers.
Critical feedback mirrors the other kits: the included gaskets function fine for most, but quality-oriented owners opt for OEM gaskets. One reviewer noted the need to apply blue Loctite to the baffle screws to prevent them from backing out over time, and another had to replace a single over-length bolt. These are minor, manageable issues that are significantly outweighed by the value and durability of replacing brittle plastic with metal.
What works
- Excellent value compared to local parts store prices
- Metallic paint finish looks great and matches the car
- Replaceable spark plug tube seals
- Includes all necessary gaskets and hardware
What doesn’t
- Included gaskets are adequate but not top quality
- Some screws in the kit may be slightly too long
- Baffle screws may require Loctite to prevent loosening
5. A-Premium Pair Left Right Engine Valve Covers
The A-Premium set is a budget-oriented solution, but it is critical to note that this kit is designed for the Nissan VQ40DE 4.0L V6 engine found in the Frontier, Pathfinder, and Xterra, NOT the VQ35DE in the 350Z. If you own a 350Z, this is not a direct fit. For those with the correct platform, it represents a highly affordable way to address oil leaks.
This kit uses plastic construction, which is a direct OEM-style replacement rather than an upgrade. It includes the left and right covers, gaskets, bolts, and oil filler cap—everything pre-assembled for convenience. Owners of Frontiers and Xterras report that the fit is “perfect” and the quality is comparable to the factory unit, making it a solid choice for a daily driver that needs a reliable fix without the expense of aluminum covers.
Feedback from the truck community emphasizes that while the plastic covers work, using a quality RTV silicone gasket maker on the mating surfaces is a wise precaution to ensure a long-lasting seal. The kit has held up well for owners over months of use, with no reported warping or leakage when installed correctly according to the torque sequence.
What works
- Very affordable complete set for the VQ40DE
- Includes all hardware and gaskets pre-assembled
- Direct OEM replacement for easy installation
- Positive long-term reviews for daily driving
What doesn’t
- Plastic construction does not solve warping issues permanently
- Does not fit the 350Z VQ35DE engine
- RTV sealant recommended for best results
6. Tuningsworld Aluminum Valve Covers (SBC)
Moving away from the VQ platform, the Tuningsworld covers are designed for the ubiquitous Chevy Small Block (SBC) engines spanning the 283, 302, 305, 327, 350, 383, and 400 cubic inch displacements from 1958-1986. These are a classic budget performance upgrade, offering a set of aluminum covers with a 1/4-inch thick billet rail for a rigid, leak-resistant seal against the cylinder heads.
Owner reviews from the classic car and truck community are largely positive, praising the “beautiful welds” and the “distinct look” these covers provide. The rigid design is specifically noted for improving the sealing surface against cast iron heads, which are prone to flexing with thinner stamped steel covers. The kit includes a pair of covers and bolts.
The most common criticism is that the bolts included with the kit are of poor quality. Several owners recommend discarding them and sourcing a high-quality set of ARP or equivalent fasteners to avoid stripped threads or broken bolts during installation. For the price, the castings themselves offer exceptional value for a classic build.
What works
- Excellent value for money entry-level aluminum covers
- Rigid design improves sealing on cast iron heads
- Decent weld quality and finish for the price point
- Fits a wide range of classic SBC engines
What doesn’t
- Bolts included in the kit are low quality
- Castings may require minor cleaning of flash
- Not applicable to Nissan VQ engines
7. Aluminum Finned Tall Valve Covers (SBC)
These tall finned aluminum covers from Autoptzxd are specifically engineered for 1987-up Chevy Small Block 305-350 engines with center bolt heads. The 3 11/16-inch height provides the necessary clearance for roller rocker arms, making them a functional upgrade for performance-oriented small block builds rather than just a cosmetic piece.
The polished aluminum finish with classic finned styling offers a vintage hot rod aesthetic. The kit comes complete with baffles, studs, bolts, and grommets for breathers, which is a comprehensive package for the price. Owners confirm they provide “more than enough clearance” for aftermarket rockers and fit securely with no leaks when installed properly.
Feedback indicates that while the covers themselves look decent and function well, the provided chrome nuts and hardware are considered low quality. One owner opted to replace them with black acorn nuts for a cleaner look, though this required a minor machine work to create clearance. Overall, these are a solid mid-range option for a track or street small block Chevy.
What works
- Tall design provides ample clearance for roller rockers
- Polished finish with classic finned styling
- Complete kit with baffles, studs, and grommets
- Good build quality for the price
What doesn’t
- Chrome hardware provided is not high quality
- Cleaning up the casting is recommended before install
- Not designed for Nissan VQ engines
8. Billet Specialties Tall Ball Milled Valve Covers (SBC)
Billet Specialties represents the premium tier of valve cover manufacturing with these American-made, ball-milled aluminum units. Designed for the Small Block Chevy, these covers are a work of art with a deep polished finish and an integrated Chevrolet script. They are baffled and include breather holes and grommets, ready for a high-end street machine or show car.
The feedback on aesthetics is universally positive—they look “great” and provide a “great look to my classic truck.” The packaging and delivery speed are praised. However, the focus on form over function is apparent in some of the critical feedback. One buyer reported that the sealing surface on the set they received had “casting marks and flashing” that were unacceptable for the price point, leading them to return the parts for fear of oil leaks.
This highlights a crucial consideration: premium billet covers offer unmatched style, but the buyer needs to be prepared to potentially true the sealing surface or run a high-quality gasket to ensure a perfect seal. For a show car where appearance is paramount, these are a top-tier choice, but for a daily driver seeking pure function, a less expensive cast aluminum cover may be more practical.
What works
- Exceptional billet construction and polished finish
- Made in the United States
- Ball milled design and Chevy logo look fantastic
- Baffled with breather provisions
What doesn’t
- Sealing surface quality control can be inconsistent
- Premium price point may not be justified for pure function
- Not applicable to Nissan VQ engines
9. Cuztom Tuning Real Carbon Fiber Side Mirror Covers
Switching to exterior accessories, the Cuztom Tuning mirror covers are designed to fit the 2003-2007 Nissan 350Z Z33. They are manufactured from real 3K carbon fiber, offering a lightweight and visually striking upgrade to the factory painted mirror caps. The self-adhesive installation is straightforward, applying directly over the existing cover for a seamless OEM-plus appearance.
Owner reviews are mixed but trend positive for those who accept the nature of a stick-on cover. Many report that the fitment is “perfect” and the carbon fiber weave is consistent and high-quality. The lightweight construction is a genuine benefit, reducing rotating mass at the highest point of the vehicle.
However, detractors point out that the fitment can be “a little off once you add the double sided tape,” requiring patience and alignment. More critically, the product does not include the 3M tape required for installation, and some buyers experienced significant fitment issues leading to returns. It is a solid product for adding a carbon fiber accent, provided you manage expectations on the adhesion process.
What works
- Made from real, lightweight carbon fiber material
- Adds a high-end performance aesthetic
- Easy stick-on installation for DIY owners
- Good weave quality and finish on most units
What doesn’t
- Adhesive tape is not included
- Fitment can be inconsistent with tape thickness
- Some units may have fitment flaws leading to returns
10. MCARCAR KIT Real Carbon Fiber Mirror Cover Caps
Similar in concept to the Cuztom Tuning covers, the MCARCAR KIT offers real carbon fiber mirror caps for the 2003-2009 Nissan 350Z Z33 coupe and convertible. These caps are made from 3K carbon fiber with a polished, UV-protected clear coating, designed to resist fading and impact damage while providing a distinct visual upgrade.
Customer feedback heavily emphasizes the “exceeded expectations” quality of the carbon fiber weave and the “laser perfect fit” when installed correctly. The UV-protected clear coat is a key differentiator, promising that the caps will not haze or yellow over time when exposed to the elements.
The primary risk with these caps is shipping damage, as they are thin carbon fiber overlays. Several reviewers reported receiving the product damaged, which significantly impacts the value proposition. Additionally, as stick-on covers, their long-term security depends on the quality of the preparation and adhesion, which is not a factor with OEM replacement parts. They are a strong cosmetic upgrade for those willing to carefully install and handle them.
What works
- High-quality pre-preg carbon fiber construction
- UV-protected clear coat prevents fading
- Perfect fit reported by many owners
- Restores faded or oxidized factory mirrors
What doesn’t
- Prone to damage during shipping
- Requires precise alignment during stick-on installation
- Duplicates the function of the factory cap
11. Generic Carbon Look Interior Center Control Covers (5PCS)
This interior trim kit from a generic brand aims to give the 2006-2009 350Z cabin a carbon fiber aesthetic with a 5-piece set covering the center console, gear box, and door handle areas. It is specifically designed for manual transmission models, which is a critical fitment detail that must be checked before purchase.
Reviews on this product are highly polarized. On the positive side, the seller is described as “very responsive” and the product can “transform” the look of the interior when it fits correctly. The stick-on overlays are easy to install, requiring only cleaning and pressing into place.
The negative feedback, however, is severe. Multiple buyers report that the fitment is “very cheap” and “doesn’t fit well at all,” particularly the passenger side pieces. Reviewers also note that the product is not a replacement part but simply a thin stick-on overlay, and it only fits the 2006-2009 facelift models, leaving early 350Z owners unable to use the product at all. It is a high-risk cosmetic accessory that depends entirely on the specific year and tolerance of your interior panels.
What works
- Can significantly update the look of the 06-09 interior
- Seller customer service is reported as positive
- Easy stick-on installation
What doesn’t
- Fitment is reported as very poor by many buyers
- Only fits 2006-2009 manual transmission models
- Cheap construction and not a true replacement part
- Passenger side pieces often do not align correctly
Hardware & Specs Guide
Aluminum vs. Plastic Construction
The factory Nissan 350Z valve covers are made from thermoplastic. Over time, heat cycling causes them to warp at the spark plug tube openings and the perimeter sealing surface. Aftermarket aluminum covers largely solve this by providing a rigid structure that maintains its shape. However, not all aluminum is equal: cast aluminum is porous and can leak if the surface isn’t properly machined, while billet aluminum is machined from solid stock and offers the best dimensional accuracy.
Gasket Material & Seal Design
The gasket creates the oil-tight seal between the cover and the cylinder head. Most aftermarket kits include a rubber or elastomer gasket. OEM Nissan gaskets are often preferred because they have a specific crush rate that accommodates the slight flex in the engine block. Using a high-quality RTV sealant at the timing chain corners is a standard precaution to prevent the most common leak points on the VQ35DE.
PCV System Integration
The Positive Crankcase Ventilation (PCV) system is critical on the VQ35DE. Upgraded valve covers must have properly designed baffles to prevent oil from being sucked directly into the intake manifold. Cheap covers often have inadequate baffling, leading to high oil consumption and carbon buildup on the intake valves. Look for covers with a well-enclosed baffle chamber behind the PCV grommet.
Spark Plug Tube Seals
Oil leaking into the spark plug wells is a hallmark of failing factory valve covers. This happens when the integrated seals on the plastic covers harden and shrink. The major advantage of aftermarket aluminum covers is the use of replaceable rubber seals. When choosing a kit, ensure the tube seals are easily sourced or included, as they are a wear item that will eventually need replacement to prevent misfires.
FAQ
What is the best material for a 350Z valve cover?
Can I use the included gaskets from an aftermarket kit?
Are plastic valve covers from the factory really that bad?
Will aftermarket valve covers fit my 2003 Nissan 350Z?
Final Thoughts: The Verdict
For most 350Z owners looking to replace failing factory covers, the winner is the MITZONE Red Aluminum Valve Cover Set because it offers the most complete package with the fewest compromises needed. The fitment is proven, the kit includes all necessary hardware, and the switch to aluminum provides a permanent solution to oil leaks. If you want the best balance of price and a pristine silver finish, grab the MILIPARTS Silver Aluminum Set. And for those tackling a full tune-up alongside their valve cover job, the CNS Valve Cover Kit provides exceptional core value, provided you budget for quality ignition coils separately.
Certification: BSc in Mechanical Engineering
Education: Mechanical engineer
Lives In: 539 W Commerce St, Dallas, TX 75208, USA
Md Amir is an auto mechanic student and writer with over half a decade of experience in the automotive field. He has worked with top automotive brands such as Lexus, Quantum, and also owns two automotive blogs autocarneed.com and taxiwiz.com.