RedMax vs. Stihl String Trimmers (Field Test)
The RedMax BCZ260TS and STIHL FS 91 R are close-use professional trimmers, but their engines differ: RedMax uses a 25.4 cc two-stroke, while STIHL’s 28.4 cc 4-MIX engine still requires a gasoline-and-oil mix. Compare them on the same ground, with approved attachments, and record work rate, fuel use, comfort, and service needs. Without measured runs, a universal winner would be guesswork.
A trimmer can feel ready in spring, then bog down, stall, or prove awkward once you start clearing a full fence line. Choosing between RedMax and STIHL is not only about engine size. Your attachment needs, dealer access, balance, and the time a machine saves on your own terrain matter just as much.
I would not call this a timed field-test result: there are no verified run times or fuel measurements to report here. Instead, this guide gives you a fair, repeatable comparison of two representative straight-shaft models, plus a scorecard you can use before you buy or replace a trimmer.
The models and what their engine labels mean
A fair comparison starts with the exact models, not broad claims about either brand. The RedMax BCZ260TS and STIHL FS 91 R are representative straight-shaft trimmers for grass and light brush. Their engine designs differ, but both use premixed fuel; check the manual for your exact market version and approved setup.
| Item | RedMax BCZ260TS | STIHL FS 91 R |
|---|---|---|
| Displacement | 25.4 cc | 28.4 cc |
| Engine type | Two-stroke | STIHL 4-MIX, four-cycle design |
| Fuel for these representative models | 50:1 gasoline-to-2-cycle-oil mix, using oil that meets the manual’s specification | 50:1 gasoline-to-2-cycle-oil mix, using oil that meets the manual’s specification |
| Main comparison point | Smaller listed displacement; compare actual cutting work and feel | Larger listed displacement; 4-MIX still uses premixed fuel |
Displacement is the volume swept by the engine’s piston. It can help describe engine size, but it does not tell you how quickly a trimmer will finish your job. Attachment, vegetation, line length, operator technique, and machine condition all affect cutting speed.
Do not confuse 4-MIX with straight gas
STIHL’s 4-MIX label describes its engine design; it does not mean the FS 91 R runs on straight gasoline. For these representative models, the listed mix is 50:1, but confirm the precise fuel and oil instructions in the manual for your machine. Never guess a ratio or use straight gas based on the engine name.
How to run a useful side-by-side field test
A field test compares both trimmers under the same conditions and records what happens. Keep the site, vegetation, cutting attachment, fuel condition, and operator as consistent as practical. If the conditions change, repeat the run or note the change instead of treating the results as directly comparable.
I would split the test into ordinary tasks you actually do: trimming lawn edges, clearing taller grass, and cutting light brush only if the exact machine, attachment, and guard are approved for that work. Do not use a blade simply because one fits. The manual determines which attachments and guards are allowed.
Set up both machines safely
Before fueling or fitting parts, confirm the model and market version, then read its operator’s manual. Check the attachment, guard, fasteners, and retention parts. Inspect the cutting head or approved blade for damage, and make sure the line type and length match the manufacturer’s directions.
Wear eye and hearing protection, gloves, long trousers, sturdy footwear, and any additional protective gear the manual calls for. Check the work area for people, pets, vehicles, glass, wire, stones, and other objects that could become projectiles. Keep bystanders outside the manual’s exclusion distance and away from the debris path.
Start, run, and record each test
Start each trimmer on clear, stable ground, following its cold- or warm-start steps. Check that it idles steadily, responds to throttle, and has no fuel leak or abnormal vibration. The attachment must not turn abnormally at idle, and the throttle trigger must return correctly. If either check fails, stop and repair the issue before testing.
Use the same operator when practical. Alternate which trimmer goes first to reduce the effect of fatigue or changing vegetation. Use controlled sweeps, the specified line length, or the approved blade technique. Keep the attachment below shoulder height, maintain secure footing, and stop before clearing a jam or crossing a path.
| Record for each run | How to measure it | Why it helps |
|---|---|---|
| Area or linear distance | Mark the plot; record area or meters of edge | Shows how much ground the machine covers |
| Elapsed time | Use the same start and finish points | Provides a work-rate comparison |
| Fuel used | Measure fuel before and after, if practical and safe | Shows fuel use for that specific task |
| Cut quality | Note missed grass, clean edges, and repeat passes | Captures finish, not just speed |
| Operator comfort | Rate balance, vibration, and fatigue after each run | Helps judge comfort over longer work |
| Service access | Note parts, dealer access, and maintenance time | Shows ownership cost beyond cutting |
Work rate means the area or distance finished per unit of time. Calculate it only when both runs use the same task and conditions. A faster run is not automatically better if it leaves a rough finish, uses much more fuel, or leaves the operator tired.
What the comparison can tell you
The most useful result is not “which brand wins?” It is which model fits your work, setup, and support options. Engine displacement alone cannot settle that question. A homeowner trimming a small yard may value easy service access, while a crew may focus more on repeat work rate and time lost to maintenance.
A practical field note should include the exact model, attachment, vegetation, weather or ground conditions if they changed, and whether the engine was cold or warm at startup. If one machine has a worn line, dirty filter, or old fuel, fix that before comparing it. Otherwise, the test may measure maintenance condition more than the trimmer.
Example test case: edging and tall grass
A useful test case is a marked strip of lawn edge followed by a separate patch of tall grass. Run each trimmer over the same length or area with the same approved attachment type, then record time, finish, fuel, and comfort. This is a test plan, not a claim that either model completed the task faster.
Keep the tasks separate. Dense grass can change the load and work rate, so do not compare its time with edging time as if they were the same job. If the grass changes across the plot, move both machines through comparable sections or repeat the run on a more even patch.
Example test case: service and downtime
For a multi-tool owner, service access can matter as much as a small difference in cutting speed. Check whether local dealers can supply the parts your model needs, how routine service is scheduled, and what the manual calls for. Record actual availability and wait time rather than relying on a brand reputation.
For commercial use, downtime affects operating cost. For occasional yard work, a nearby service option and clear maintenance instructions may be more useful than a small performance difference you cannot measure reliably.
Fuel, maintenance, and seasonal starts
Preventive care reduces avoidable starting and running problems, but exact steps vary by model. Use fresh fuel of the specified type and ratio, and follow the manual’s instructions for mixing, handling, and storage. Do not assume the same draining or stabilizer method applies to every fuel-system design.
After each test block, shut the engine off, wait until the attachment stops, and let hot parts cool. Clear grass from the guard, cutting head, air-intake area, and cooling surfaces. Inspect the line or blade, fasteners, guard, air filter, fuel lines, and visible areas for leaks or damage. Replace damaged parts with approved parts.
Do not guess carburetor settings. Use the maker’s specified idle and maximum-speed procedure and proper equipment. Never exceed the stated maximum engine speed. If the trimmer will not idle or accelerate correctly, arrange qualified service rather than making blind adjustments.
Before seasonal use, inspect the fuel lines, filter, air filter, attachment, guard, controls, and fasteners. Use fresh fuel at the correct ratio. If the machine has been stored with fuel, follow its manual’s return-to-service guidance; a carburetor problem should not be “fixed” by changing the mix ratio.
Choosing between RedMax and STIHL
A model choice should reflect your terrain, attachment needs, comfort, service options, and measured results. These two examples have different engine designs and listed displacement, but those details do not prove one will cut faster or last longer. Match the machine to the work, then verify the comparison with a safe test.
Before buying, confirm the exact model’s manual and locally available attachments. Compare how each machine feels in a short, safe test if a dealer allows one. Consider whether the controls and balance suit you, and whether local service can reduce downtime. For repeat commercial jobs, include maintenance time and parts access in your decision.
Stop work if an attachment is damaged, the guard is missing or incorrect, or bystanders enter the exclusion area. Line and blades can throw stones, wire, or broken parts at high speed. Do not remove a guard to fit a larger attachment or widen the cut. Correct the setup before restarting.
Bottom line: pick the trimmer that completes your real tasks cleanly, feels manageable, and can be serviced where you work. Use recorded results, not displacement or brand loyalty alone. Before each season, verify fuel, attachment, guard, and controls against the manual.
Frequently asked questions
Which has more engine displacement, the RedMax BCZ260TS or STIHL FS 91 R?
The STIHL FS 91 R is listed at 28.4 cc, compared with 25.4 cc for the RedMax BCZ260TS. That alone does not establish which one will finish a task faster.
Does the STIHL FS 91 R use straight gasoline?
No. Its 4-MIX label does not mean it runs on straight gasoline. The representative FS 91 R setup uses a gasoline-and-2-cycle-oil mix; check the exact manual for the required fuel.
What fuel mix do these two representative models use?
The specified mix is 50:1 when using oil that meets the manufacturer’s requirements. Verify the manual for your model and market version before mixing fuel.
Can I compare them using different cutting attachments?
Not fairly. Use the same attachment type where both manuals approve it, and keep the guard and setup correct for each machine. Never fit an unapproved attachment to make the comparison match.
What should I measure in a trimmer field test?
Record the area or distance cut, elapsed time, fuel used, cut quality, operator comfort, and service needs. Keep the site and vegetation as similar as possible.
Which trimmer is better for tall grass?
There is no universal answer from the listed engine sizes. Use an attachment approved for the task, then compare both machines on similar grass with the same safe method.
Should the cutting attachment turn at idle?
It should not turn abnormally at idle. If it does, or if the throttle fails to return, stop using the trimmer and have it checked.
Can I adjust the carburetor to improve a poor field-test result?
Do not guess at carburetor settings. Follow the manufacturer’s procedure and speed limits, or use qualified service if the trimmer does not idle or accelerate correctly.
What should I inspect before storing a trimmer for the season?
Clean and inspect the machine, attachment, guard, controls, filters, fuel lines, and fasteners. Follow the model manual for fuel handling and storage; procedures can differ.
What is the safest response to a damaged attachment or missing guard?
Stop work and do not restart until the correct, approved parts are fitted and secure. Keep people outside the exclusion area because debris or broken parts can cause severe injury.
(This article was written by one of our staff writers, Harrison Croft. Visit our Meet the Team page.)
