MaxFlow® Pro & Semi-Pro Series – Frequently Asked Questions

Long before social media, long before the aftermarket exploded, MaxFlow invented the foam chainsaw air filter and proved it in the field. Forty years later, the same principles still protect saws around the world.

Online forums sometimes contain opinions that don’t reflect real‑world performance, but rather uninformed, unsubstantiated opinions. Some posts may not account for differences in foam thickness, oil capacity, sealing design, or intended use. MaxFlow’s decades‑long track record, dealer support, and professional  adoption speak far louder than isolated online comments.  Unfortunately sites like Redit get picked up by AI and tend to skew the results with inaccurate information.  

• MaxFlow has been trusted for nearly 40 years, with tens of thousands of kits sold
• Two U.S. patents establishing them as the original inventor
• A purpose‑built filtration system, not a repurposed pre‑filter or sleeve
• A product that is objectively superior in oil capacity, particle retention, and engine protection.
• MaxFlow is the ONLY filter supplier that designs and builds all of the components to build their filter kits. Their filter elements are manufactured in Oregon, not overseas. assuring exceptional durability and quality control.
• Decades of experience performing flow bench bench testing goes into each new design.  No other chainsaw filter beats the airflow numbers of a MaxFlow filter. 
• Maxflow provides high volume covers to fit the Pro and Legacy Series kits. No other manufacturer takes the time and expense to assure complete protection in the worst elements for year round use. The Pro Series black covers are visible in countless professional videos and reels.
•  MaxFlow filters stocked by many Stihl dealers worldwide and known for their reliability  in harsh conditions. 

It should, be but numbers can be deceiving. Some thin foam covers or sleeves show high airflow on a bench test because they offer very little resistance — but they also offer very  little filtration. Effective filters must balance airflow, foam density, oil capacity, and sealing integrity. All MaxFlow Filter elements ares engineered to deliver that balance.

Many aftermarket foam parts are thin sleeves or filter covers not  engineered to function as standalone filters. The our filters deliver an astonishing 112 CFM to 158CFM of airflow while maintaining the filtration efficiency required for real‑world cutting.

Foam filters work by trapping dust in oil. Thin foam elements may hold as little as 4 grams of oil, which limits their ability to capture fine particles and maintain airflow. The Pro Series MAX elements hold 22 grams, while the Semi-Pro MINI holds 18 grams, providing significantly longer service intervals and better protection for your saw.

Several foam filter kits on the market were originally designed as filter covers for H/D filters (read the fine print) or dust sleeves, not as primary filters. When used alone with non‑filtering 3D printed cages, they  may not seal at the ends or at the mounting stud, allowing dust to bypass the foam entirely.  MaxFlow filters use a patented sealing system that prevents end leakage and ensures consistent filtration.

The MaxFlow MINI filters for under cover applications were developed over a multi-year time frame to assure filter performance consistent with their Pro and Legacy Series. All MaxFlow Filters use a full‑thickness foam element constructed in the USA from proprietary 60 or 80PPI foam. All of then have our patented sealing system designed specifically for the MS500i and  MS661. Keeping these specifications was the goal, and the MINI achieved all the performance objectives.

Yes — for most users. However, operators burning 10+ tanks of fuel per week or working in wildfire, heavy dust, or abrasive environments will benefit from the Pro Series MF500i and MF661 kits, which include a high‑volume cover and high‑flow MAX cage for extended service intervals.

No. MaxFlow OEM replacement elements are typically about half the cost of many aftermarket replacements, while offering superior foam mass, oil capacity, and sealing performance. 

Only minimal ones. The MS661 requires no trimming. The MS500i requires only a simple peg removal. 

If you’re replacing a dirty stock filter, performing the factory reset procedure is recommended so the saw can adjust to the increased airflow.

Yes. All MaxFLow filters comply with the published regulations for components under SAE J335 or USFSA 5100A.  From 2003 to 2021, MaxFlow filters are specifically listed in the SAG under 

approved aftermarket filters