Why Storage Preparation Matters
Petrol degrades in 30–90 days. Old fuel leaves varnish deposits in the carburettor. Water absorption by ethanol-blended petrol corrodes metal components. An engine oil not changed before storage circulates acidic combustion by-products through bearings all winter. These three factors are responsible for almost every storage-related failure.
Step 1 — Final Run Before Storage
Run the engine at normal operating load for the last time, letting it reach full operating temperature. This burns off condensation in the oil and prepares the fuel system for treatment.
Step 2 — Fuel Treatment (Choose One Method)
Method A (Fuel Stabiliser): Add fuel stabiliser to the tank at manufacturer's recommended ratio (typically 1:250). Run the engine for 5–10 minutes to draw treated fuel through the carburettor. This protects stored fuel for 12–24 months and prevents carburettor varnishing.
Method B (Drain the Fuel System): Turn off fuel tap (if fitted), run the engine until it stops from fuel starvation, then open the carburettor drain screw to empty the float bowl. An empty fuel system cannot develop varnish. Preferred by professionals for long-term storage.
Step 3 — Oil Change
Change the oil before storage, not when you take it out in spring. Hot oil drains more completely. Fresh oil has no acidic by-products that would corrode bearings over winter. Fill to the correct level with fresh recommended-grade oil.
Step 4 — Cylinder Fogging
Remove the spark plug. Spray a tablespoon of fresh engine oil into the spark plug hole. Pull the recoil starter slowly 3–4 times to distribute oil over the cylinder walls, piston and rings. This prevents corrosion on these surfaces which otherwise have no oil film during storage. Reinstall the spark plug — but leave the lead disconnected to prevent accidental starts.
Step 5 — External Corrosion Prevention
Wipe all exposed metal surfaces (cylinder fins, frame, exhaust) with a clean cloth lightly oiled with WD-40 or a corrosion inhibitor spray. Clean the air filter. Check and tighten all external bolts and screws.
Step 6 — Storage Location
Store in a cool, dry, well-ventilated location. Avoid damp sheds. Cover with a breathable cloth (not plastic — trapped moisture under plastic promotes rust). If possible, elevate off a concrete floor — concrete draws moisture.
Spring Startup After Proper Storage
A properly prepared engine should start within 2–3 pulls. Add fresh petrol, reconnect the spark plug lead, choke fully closed, and pull. The cylinder fogging oil will produce a small puff of white smoke on the first few starts — this is normal and clears quickly.
FAQ
How long can petrol sit in a stabilised tank?
With quality fuel stabiliser: 12–24 months. Without stabiliser: 30–60 days before degradation begins. In E10 blends (10% ethanol): even shorter — 30 days maximum without stabiliser.