Owner’s manual
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Should I use 87 or 91 gas for lawn mower?
For the Craftsman 917376591 gas walk-behind mower, we recommend using fresh regular unleaded gasoline (87 octane). Higher octane (like 91) does not improve performance in a mower engine; fuel freshness and proper storage matter far more for reliable starting and smooth running.
What to use (and what to avoid)
- Use fresh, clean unleaded gasoline; 87 octane is the right choice for typical walk-behind mower engines.
- Avoid old fuel; stale gas is a common reason a mower will not start.
- Avoid leaving fuel sitting for long storage periods; ethanol-blended fuels can attract moisture and cause fuel-system damage during storage.
- Do not add engine or carburetor cleaner products directly into the fuel tank.
- If the mower will sit 30 days or longer, plan to empty the fuel system before storage.
Storage guidance for fuel (30 days or longer)
The 917376591 owner documentation calls out fuel storage as a key reliability issue. Use these steps to prevent hard-starting next season:
- Empty the gas tank.
- Start the engine and let it run until the fuel lines and carburetor are empty.
- Refill with fresh gasoline when you put the mower back into service.
- Replace rusty gas cans; rust and dirt in fuel cause problems.
For the full storage procedure and safety notes, follow the 917376591 owner's manual.
Quick comparison: 87 vs 91 for a walk-behind mower
| Fuel choice | What it changes | What it does not change |
|---|---|---|
| 87 octane (regular) | Normal operation when fuel is fresh | Power increase over spec |
| 91 octane (premium) | Usually nothing noticeable | Easier starting, cleaner running, longer engine life |
Why it matters
Most “fuel problems” on walk-behind mowers come from stale gas, moisture contamination, or storage habits, not octane rating. Using fresh fuel and storing it correctly helps protect the carburetor, fuel lines, and starting system.
Last updated: January 2026
What model number is a Craftsman 6.75 lawn mower?
If you have a Craftsman mower described as “6.75,” the exact model number depends on the ID tag on your mower. For the Craftsman walk-behind mower covered by this page, the model number is 917.376591 (often written as 917376591); confirm it on the mower label and in the 917376591 owner's manual.
Where to find the model number on the mower
We recommend checking the product ID label first, then matching it to the manual.
- Look on the rear of the deck near the discharge opening
- Check the top of the deck near the engine mounting area
- Look near the handle bracket or height-adjuster area
- Match the number format (with or without a dot), for example 917.376591 vs 917376591
“6.75” vs model number: what it means
“6.75” is typically an engine power class used in listings and decals; it is not the mower’s full model identifier. The model number is what you need to get the right Craftsman parts (blade, drive belt, wheels) and the correct diagrams.
| What you see | What it’s used for | What to use for parts |
|---|---|---|
| “6.75” | General engine power class | Not reliable for parts lookup |
| 917.376591 / 917376591 | Exact mower identification | Best for parts and manual matching |
If you are replacing parts, match by model number
Once you confirm the mower is model 917376591, use model-matched parts to avoid fit issues.
- For cutting performance, match the blade to the deck size and mounting pattern
- For self-propel problems, match the belt and drive components to the transmission setup
- For wheel issues, match the wheel and tire size and hub style
Common model-matched examples for this mower include the husqvarna lawn mower 22-inch deck 3-in-1 blade 532421825 and the lawn mower ground drive belt 532196853.
Why it matters
Using the correct Craftsman model number prevents ordering the wrong walk-behind mower parts and helps ensure safe operation, proper blade fit, and correct drive performance.
Last updated: January 2026
What is the average lifespan of 917376591?
A Craftsman walk-behind mower like model 917376591 typically lasts 8 to 12 years with normal residential use and routine maintenance. Lifespan is driven more by maintenance (oil, blade, belt, and cable condition) than by the deck itself; follow the 917376591 owner's manual maintenance schedule.
What affects lifespan the most
- Oil changes and clean oil level (engine wear is the #1 limiter)
- Blade condition and balance (reduces vibration and crankshaft stress)
- Drive system wear (belt, pulleys, transmission, and drive control cable)
- Deck care (cleaning, rust prevention, avoiding impacts)
- Storage habits (dry storage, stabilized fuel for off-season)
Common wear items to plan for
These parts often determine whether the mower still cuts and self-propels well:
| System | Typical wear symptom | Example part for this model |
|---|---|---|
| Cutting | Poor cut, tearing grass, vibration | Husqvarna lawn mower 22-inch deck 3-in-1 blade 532421825 |
| Self-propel | Slipping or no drive | Lawn mower ground drive belt 532196853 |
| Controls | Engine zone control or drive control feels loose | Control cable (inspect routing and adjustment) |
| Wheels | Uneven height, wobble | Wheel and tire components (inspect tread and bushings) |
Maintenance targets that extend life
- Change engine oil at the intervals listed in the manual; keep oil at the correct level.
- Sharpen or replace the blade when it nicks or rounds over; always keep it balanced.
- Keep the underside of the deck clean; avoid spraying the engine directly with water.
- Inspect the drive belt each season for glazing, cracking, or stretching.
- Use fresh fuel and stabilizer for storage; run the mower dry if your manual recommends it.
Why it matters
Most “worn out” mowers still have a solid deck and handle assembly; performance drops because the blade, belt, cables, or wheels are worn. Replacing those wear items on time keeps cut quality high and prevents bigger failures.
Last updated: March 2026
