BFO OPXM4K Benz Connecting Rod 3.0L 3.5L M272
fits model: Cls300, Cls350. make: Mercedes. year: 2005–2010.
( Brand: Bfo ), ( Manufacturer Part Number: OPXM4K ), ( California Prop 65 Warning: California Prop 65 Warning ), ( Finish: Polished ), ( Fitment: For Mercedes-benz C280/c300/c350/e230/e280/e300/e350, For Mercedes-benz Clk280/clk350/clk350/cls300/cls350, For Mercedes-benz Glk300/glk350/ml300/ml350/ml300, For Mercedes-benz Ml300/ml350/ml450/r280/r300/r350, For Mercedes-benz S280/s300/s350/s400/sl300/sl350, For Mercedes-benz Slk280/slk300/slk350 2004-2015 ), ( Manufacturer Warranty: 2 Years ), ( Material: Steel ), ( Oe/oem Part Number: A2730300620, A2730300820, 2730300620, 2730300820 ), ( Performance Part: Yes ), ( Type: Connecting Rod ), ( Vintage Part: No )
Review BFO Connecting Rod Assembly Mercedes benz 3.0l 3.5l fits CLS300 CLS350 2005–2010
The **BFO OPXM4K Forged Steel Connecting Rod** is a high-performance, precision-engineered replacement part designed exclusively for the Mercedes-Benz CLS-Class models (CLS300 and CLS350) equipped with the **M272 3.0L and 3.5L inline-six engines** produced between **2005 and 2010**. Crafted from **ultra-high-strength forged 4340 chromium-molybdenum alloy steel**, this connecting rod is engineered to withstand the extreme stresses of high-performance driving, ensuring durability, reliability, and optimal power transfer within the engine s crankshaft assembly. Unlike standard aftermarket rods, the OPXM4K features **laser-machined surfaces** for superior fitment, eliminating clearance issues that can lead to premature wear or failure. Its **precision-ground journals** and **optimized wall thickness** enhance rigidity while reducing vibration, contributing to a smoother, more efficient combustion cycle. The rod is **heat-treated to an exacting hardness specification**, balancing strength with fatigue resistance to handle the torque demands of both stock and modified engines. Compatible with the **M272 s specific rod bolt pattern and crankshaft interface**, this rod is a direct drop-in replacement, eliminating the need for engine disassembly or modification. Whether restoring a classic CLS to factory specifications or upgrading a high-performance build, the BFO OPXM4K connecting rod delivers the structural integrity and performance consistency required for long-term reliability in demanding applications. Built to meet or exceed OEM standards, this rod is a trusted choice for enthusiasts and mechanics seeking a dependable solution for maintaining or enhancing the power output of the M272 engine family.
### **Pros and Cons of Buying a BFO OPXM4K Connecting Rod for a Mercedes-Benz CLS 300/CLS 350 (M272, 2005 2010)**
#### **Pros:**1. **High-Quality Material and Construction** BFO (Bilstein-Forged-Optimized) rods are made from high-grade forged steel, ensuring superior strength and durability compared to cast rods. This reduces the risk of catastrophic failure, which is critical for high-performance or heavily modified engines.
2. **Precision Machining** These rods are CNC-machined to exact specifications, minimizing stress concentrations and improving fatigue resistance. This is particularly beneficial for engines running at higher RPMs or under heavy loads.
3. **Compatibility with M272 Engine** The OPXM4K is specifically designed for the 3.0L and 3.5L M272 V6 engines found in the CLS 300/CLS 350 (2005 2010). It matches the rod length and bolt pattern required for these applications, ensuring proper fitment and performance.
4. **Improved Strength for Forced Induction** If your engine is turbocharged or supercharged, these rods provide the extra strength needed to handle increased cylinder pressures without bending or cracking.
5. **Warranty and Reputation** BFO is a well-respected brand in the aftermarket, offering warranties on their products. This provides peace of mind in case of manufacturing defects.
6. **Potential for Increased Reliability** Original equipment manufacturer (OEM) rods can degrade over time, especially under aggressive driving conditions. Upgrading to BFO rods can restore or enhance reliability, particularly if the engine has seen significant mileage or modifications.
7. **Easier Installation** Since these rods are direct replacements for OEM parts, they can often be installed without major engine disassembly, though some labor may still be required.
---
#### **Cons:**1. **Cost** BFO rods are significantly more expensive than OEM or generic aftermarket rods. For a set of four, the price can range from **$800 to $1,500 **, depending on the retailer and whether additional components (like bolts or bearings) are included. This makes them a substantial investment compared to stock or budget aftermarket options.
2. **Installation Complexity** While not overly difficult, replacing connecting rods requires disassembling the engine, removing the crankshaft, and carefully installing the new rods with proper alignment. This is a job best left to experienced mechanics unless you have significant engine-building experience.
3. **Potential Overkill for Stock Applications** If your engine is running stock or lightly modified (e.g., minor tuning without forced induction), the stock rods may still be adequate. Upgrading to BFO rods may not provide noticeable performance benefits but does offer a safety margin for future modifications.
4. **Additional Components May Be Required** Upgrading rods often necessitates upgrading other critical components to match, such as:- **Crankshaft** (if it s worn or not already a high-quality part)
- **Main bearings and caps** (to ensure proper support)
- **Pistons and rings** (for optimal performance)
- **Rod bolts** (BFO often recommends using their own bolts or high-quality alternatives like ARP or EBC)
This can add to the overall cost and complexity of the project.
5. **Time-Consuming Project** A full rod replacement is a labor-intensive process that can take **10 20 hours** or more, depending on the engine s condition and the mechanic s experience. This may require removing the engine from the vehicle, which adds to the cost and downtime.
6. **Risk of Improper Installation** If not installed correctly, even high-quality rods can fail. This includes issues like:- Incorrect rod end clearance
- Misaligned rod caps
- Improper torque on bolts
- Failure to check for crankshaft or bearing wear
Poor installation can negate the benefits of the rods and even cause damage.
7. **Limited Immediate Performance Gain** Unlike components like turbochargers or exhaust systems, rods primarily enhance reliability and durability rather than outright power. The performance benefits are indirect (e.g., allowing for more aggressive tuning without failure).
---
### **Conclusion:**Upgrading to **BFO OPXM4K connecting rods** for your Mercedes-Benz CLS 300/CLS 350 (M272) is a **wise investment** if you prioritize **long-term reliability, forced induction, or aggressive driving conditions**. These rods offer superior strength, precision, and compatibility, making them an excellent choice for engines that are heavily modified, turbocharged, or approaching high mileage. However, the **high cost, labor-intensive installation, and potential need for additional upgrades** mean this is not a decision to be taken lightly.
If your engine is **stock or lightly modified**, the stock rods may still suffice, and the cost of BFO rods may not be justified. However, if you plan to **push the engine beyond stock limits** (e.g., forced induction, high-RPM tuning, or aggressive driving), the BFO rods provide a **significant safety upgrade** and can prevent catastrophic failures.
---
### **Recommendation:** 1. **If your engine is stock or lightly modified:**- **Consider sticking with OEM rods** unless you notice signs of wear (e.g., oil consumption, knocking, or visible rod damage). Regular maintenance (oil changes, timing belt inspection) may be sufficient.
- If you re unsure about rod condition, have a mechanic inspect the rods during an engine teardown for wear or cracks.
2. **If your engine is turbocharged, supercharged, or heavily modified:** - **Upgrade to BFO OPXM4K rods** as part of a **comprehensive engine rebuild**. Pair them with:- A **high-quality crankshaft** (e.g., Eagle or JE)
- **ARP or EBC rod bolts**
- **Matching pistons and bearings**
- **Proper lubrication (e.g., synthetic oil with high viscosity index)**
- Budget for **professional installation** to ensure correctness.
3. **If you re on a budget but want reliability:** - Explore **alternative high-quality rod options** such as:- **Eagle rods** (another reputable brand)
- **JE rods** (known for durability)
- **OEM replacement rods** (if available and in good condition)
- These may be slightly cheaper than BFO while still offering significant improvements.
4. **Before purchasing:**- **Verify the exact year and engine specifications** (e.g., 3.0L vs. 3.5L, turbo vs. NA) to ensure the OPXM4K is the correct part.
- **Check for rod wear** by removing the oil pan and inspecting the rods for cracks, bending, or excessive wear on the journals.
- **Consult a Mercedes specialist** to confirm whether rod replacement is necessary or if other issues (e.g., crankshaft wear, bearing failure) are the root cause of problems.
### **Final Verdict:**The **BFO OPXM4K rods are one of the best aftermarket options** for the M272 engine, offering a strong balance of quality and performance. **They are worth the investment for forced induction or high-mileage engines**, but for stock applications, the cost may not be justified. Always pair rod upgrades with a **full engine rebuild** for optimal results.
Details:
Material: Metal. Built to handle the demands of your luxury vehicles performance needs. OE/Part number. Guaranteed Fitment Always the correct part.
Connecting Rod Assembly for Mercedes-Benz CLS300 CLS350 3.0L 3.5L M272 2005 -2010. 7th, After Apr. PERFORMANCE RELIABILITY: Restores optimal engine performance and efficiency, ensuring smooth power delivery reducing vibration.
Color: Silver. Fast Shipping. Showing as the picture. Save time and money with this perfectly matched component.
Check OE numbers to ensure proper fitment. Telephone number. Package included. For Car model is for reference only; actual compatibility may vary.
1 Engine Connecting Rod. Installation should be done by a qualified technician. HASSLE-FREE INSTALLATION: designed as a direct drop-in replacement, allowing for straightforward installation without modifications.
Full physical.
part #: opxm4k price
- $84.76
specifications pistonrinro:
- for models: Cls300, Cls350
- for makes: Mercedes
- for years: 2005-2010
- brand: Bfo
- mpn: Opxm4k
- california prop 65 warning: California Prop 65 Warning
- finish: Polished
- fitment: For Mercedes-benz C280/c300/c350/e230/e280/e300/e350, For Mercedes-benz Clk280/clk350/clk350/cls300/cls350, For Mercedes-benz Glk300/glk350/ml300/ml350/ml300, For Mercedes-benz Ml300/ml350/ml450/r280/r300/r350, For Mercedes-benz S280/s300/s350/s400/sl300/sl350, For Mercedes-benz Slk280/slk300/slk350 2004-2015
- manufacturer warranty: 2 Years
- material: Steel
- oe/oem part number: A2730300620, A2730300820, 2730300620, 2730300820
- performance part: Yes
- type: Connecting Rod
- vintage part: No
returns pistonrinro:
- policy: Returns Accepted
- paid by: Seller
- time: 30 Days
seller pistonrinro:
- # reviews: 3355
- rating: 99.7%
- city: Elk Grove Village, Illinois
payments pistonrinro:
- credit card: Diners-club
- wallet: Apple-pay
- other
offer pistonrinro:
- options: Ship-to-home
- started: April 16, 2026
- sold: 0
- best offers: True
- quantity: 1
- availability: In Stock
shipping pistonrinro:
- service: FedEx Ground / FedEx Home Delivery
- type: Fixed
- transit: 2-5 Days
- cost: $0.00
- class: Standard
- carrier: FedEx
general pistonrinro:
- condition: New
- Car Truck Parts Accessories > Engines Engine Parts > Connecting Rods Parts
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