STIHL MS 251 Gas Chainsaw 45.6cc 18 in.

The STIHL MS 251 is a mid-size gas chainsaw aimed at homeowners, acreage owners, and light professional users who need dependable cutting power for firewood prep, storm cleanup, and general property maintenance. Its 45.6cc STIHL 2-MIX engine strikes a balance between portability and cutting force, making it equally comfortable felling small trees or bucking rounds for the woodpile.

Efficient 2-MIX engine

The STIHL 2-MIX engine technology improves combustion efficiency, which translates into lower fuel consumption and reduced exhaust emissions compared with older two-stroke designs, without sacrificing the torque needed for demanding cuts.

Reduced-maintenance air filtration

A pre-separation air filter routes larger debris away from the filter element before it ever reaches it, extending filter life and keeping the engine breathing cleanly even in dusty, sawdust-heavy conditions.

Vibration-dampened handling

STIHL's anti-vibration system isolates the engine and cutting attachment from the handles, reducing operator fatigue during long sessions of bucking or limbing.

Key features

• 45.6cc STIHL 2-MIX engine delivering roughly 2.9 bhp (2.2 kW)
• 18 in. guide bar paired with a low-kickback .325 in. pitch STIHL RM3 saw chain
• Tool-free, bayonet-style fuel cap for quick refueling
• STIHL Ematic bar lubrication system that cuts oil consumption by up to 50 percent
• Side-access chain tensioning and a single-lever master control for choke, throttle lock, and stop functions

Specifications

Frequently asked questions

What fuel mix does the MS 251 require?

Like all STIHL gas chainsaws, the MS 251 runs on a 50:1 mix of unleaded gasoline (89 octane or higher, up to E10) and STIHL two-stroke engine oil. Using pre-mixed STIHL fuel or accurately measuring the ratio helps protect the engine and keeps warranty coverage intact.

Does the MS 251 come with bar oil or fuel included?

No. Like most gas-powered chainsaws, the MS 251 ships as a powerhead with bar and chain only; two-stroke fuel mix and bar and chain oil are sold separately.

Is the 18 in. bar the only option for this saw?

STIHL offers the MS 251 platform with multiple bar length options depending on the retailer configuration; this listing is equipped with the 18 in. bar and matching low-kickback chain.

What is in the box

Each kit includes the STIHL MS 251 chainsaw powerhead, an 18 in. guide bar, a low-kickback .325 in. pitch STIHL RM3 saw chain, and the owner's manual. Two-stroke fuel mix and bar and chain oil are not included.