Storage and winterization: three failure modes, three clocks

Tires off the ground where practical

Raising the wheels or rolling the machine now and then prevents flat spots. If the tires stay on the ground, inflate them to the maximum pressure printed on the sidewall, typically 5 to 7 psi above riding pressure, and set them back to riding pressure before the first ride.

Maintenance questions

Does stored gasoline go bad from phase separation or from just going stale?

Research funded by the U.S. Department of Energy found that in typical storage conditions, the gasoline itself oxidises and loses volatility well before enough water is absorbed to cause ethanol phase separation, so ordinary staleness, not the more dramatic phase-separation failure most owners have heard about, is usually the first problem to show up.

Is fuel stabilizer backed by a standard?

No: there is no SAE, API or ASTM standard governing fuel stabilizer formulation or performance claims. It is sound, widely recommended manufacturer guidance and a real product category, but it is not backed by a standards body the way an oil rating or tire size is.

Should I run the tank empty or full for storage?

Both are legitimate approaches and manuals differ on which they recommend for a given fuel-delivery type. A full tank minimizes the air space where oxidation and moisture absorption happen; an empty, stabilized-and-drained system removes the fuel from the equation entirely. Follow your own manual's specific recommendation instead of assuming one approach is universally correct.

Why do batteries die in storage more than in use?

Self-discharge and sulfation are electrochemical processes that continue whether or not the machine runs, and both accelerate with heat and a low state of charge: a battery simply sitting is actively degrading, not merely idle. A charged, maintained battery in regular use rarely reaches the depleted state that causes storage failures.

Does disconnecting the battery prevent storage damage?

It slows self-discharge by removing the small parasitic draws a connected electrical system creates, but it does not stop self-discharge entirely, since that process is internal to the battery. A smart maintainer that keeps the battery at full charge throughout storage is a more complete defence against sulfation than disconnection alone.

Is E10 gasoline worse for storage than non-ethanol fuel?

Ethanol-blended fuel is hygroscopic in a way non-ethanol fuel is not, which is the real mechanism behind phase separation specifically. But the research above found general staleness is usually the first failure regardless of blend, so ethanol content changes which specific failure mode arrives, not whether the fuel degrades at all over a long storage period.

How long can a machine sit before storage prep matters?

There is no single threshold. But a few weeks of ordinary staleness risk becomes a different, multi-clock storage risk (fuel, battery, tire flat-spotting) somewhere around the one-to-two-month mark for most machines, which is why "seasonal storage", not "between rides" is the practical dividing line this page and most manufacturer guidance use.

Do I need to change the oil before storing a machine, or after taking it out of storage?

Before, if the oil is due or close to it: used oil carries combustion byproducts and acids that continue reacting with internal components even while the machine sits unused, so storing on fresh oil avoids months of that slow chemical exposure. If the oil was recently changed and well within its interval, storing on it and changing on the normal schedule afterward is also fine.

Should tires be inflated to a different pressure for storage than for riding?

Some manufacturers recommend a slightly higher pressure for long-term storage specifically to reduce flat-spotting risk from the tire's own weight sitting on one contact patch for months: check your manual, since this is not universal across every machine, and reducing pressure for storage is never the correct direction.

Does covering a machine during storage matter as much as the fuel and battery prep?

It addresses a different risk entirely, UV and dust exposure to plastics, seats and finishes, and not the chemical and electrochemical clocks this page focuses on. A breathable, machine-specific cover is worth using. It does not replace fuel stabilization or battery care. A covered machine with untreated fuel and a disconnected, unmaintained battery still has both of those problems waiting at the end of the season.

Is indoor storage necessary, or is a covered outdoor spot good enough?

Indoor, climate-stable storage reduces the temperature swings that accelerate both fuel oxidation and battery self-discharge. So it is meaningfully better where available, but a well-covered outdoor spot with the same fuel stabilization and battery maintenance steps still protects against the two clocks this page covers, just with somewhat faster degradation from wider temperature swings than an indoor space would produce.

Does storage prep differ for a two-stroke versus a four-stroke engine?

The fuel-system prep is largely the same, stabilize or drain. But a two-stroke's premix or injected oil adds a wrinkle: fuel left in the system over a long storage period separates unevenly if it was premixed instead of injected, so running the carburetor dry, not leaving stabilized premix fuel in it is the more common recommendation on a two-stroke specifically. Check your manual, since practice varies by manufacturer.

Brake fluid and coolant

The third clock: moisture and inhibitor depletion that runs whether or not the machine moves.