Can I use last year's 2-stroke mix?

It's risky. Premixed 2-stroke fuel starts to degrade in about 30 days, and after a winter in the shed the gas oxidizes and the ethanol can absorb water. Drain the old mix and run a fresh batch. Stale fuel is the #1 cause of spring no-starts.

How much oil do I add per gallon for spring startup?

The same ratio your engine always calls for; mixing fresh fuel doesn't change it. At 50:1 add 2.56 oz per gallon, at 40:1 add 3.2 oz. Use the calculator below for your exact gas-can size.

My trimmer won't start after winter, what first?

Almost always old fuel and a fouled plug. Drain the tank, mix fresh premix at the correct ratio, replace or clean the spark plug, and check the primer bulb and air filter before assuming anything worse.

Spring Startup: Getting 2-Stroke Lawn & Garden Equipment Ready for the Season

When the growing season starts, the string trimmer, mower, and leaf blower come out of the shed, and half of them won’t start on the first pull. The culprit is almost never the engine. It’s the fuel that’s been sitting in the tank all winter. Here’s how to get your 2-stroke lawn and garden equipment running again, cleanly, the first time.

Why last year’s mix is your problem

Premixed 2-stroke fuel has a short shelf life. The gas oxidizes in about 30 days, and pump gas with ethanol pulls in moisture as it sits, so after a winter in an unheated shed the mix in your trimmer is gummy, watery, and down on octane. That’s what fouls the plug, clogs the carb, and turns the first warm weekend of the season into a no-start.

The fix is simple: drain the old mix and run a fresh batch at the correct ratio.

Mix a fresh batch for the season

Your ratio doesn’t change just because it’s spring; a 50:1 trimmer is still 50:1. What changes is that you want fresh fuel in the right amount so you’re not storing leftovers for another month. Pick your gas-can size and ratio:

Fuel → oil Oil → fuel

Amount of fuel

Equipment (optional)

Mix ratio

Custom ratio (X : 1)

Add this much oil

12.8 oz

≈ 378.54 ml

Add 12.8 oz of 2-stroke oil to 5 gal of gas at a 50:1 ratio.

If you’re not sure of your ratio, check the fuel cap or the owner’s manual, and when in doubt, the richer ratio (more oil, e.g. 40:1 over 50:1) is the safer guess. See the 50:1 and 40:1 reference pages, or the printable mix charts, for the full tables.

Spring startup checklist

Drain the old fuel from the tank and the carburetor bowl (run it dry, or empty it). Don’t top off stale mix with fresh.
Mix fresh premix at your ratio into an approved can, shake it, then fill the tank.
Pull or replace the spark plug. A winter of stale fuel usually leaves it fouled; a fresh plug is a cheap fix for a hard-starting engine.
Check the air filter and primer bulb. A cracked primer bulb or a clogged filter mimics fuel-mix problems.
Prime and start. Expect a little smoke on the first run as it clears out; that’s normal.

For equipment-specific tips, see the string trimmer, lawn mower, and leaf blower guides.

Time it to your actual growing season

There’s no point firing everything up in March if your ground is still frozen, and no point being caught off guard when the season starts three weeks earlier than you expected. The first mow, the first trim, and the first real yard work all track your local climate, so it helps to know your window before you pull equipment out of storage. If you’re planning the season, look up your USDA planting zone and local frost dates so you time the first startup (and the first planting) to your area rather than the calendar.

Get the fuel fresh and the timing right, and everything from the trimmer to the mower starts on the first pull.