A UK winter is hard on stored vehicles. Damp, frost, flat batteries and degrading fuel are the four big enemies. A weekend of preparation in late October saves a fortune in March — here's the routine that works.
Drain the water system, fully
Open every tap, hot and cold. Open the boiler drain valve (Truma frost drain operates automatically below 3°C but back it up manually). Open the waste tank drain. Run the pump dry for two seconds (no longer) to clear the pipes. Leave taps open all winter so any residue can't freeze and split a fitting.
Battery: trickle, don't disconnect
Disconnecting and leaving a leisure battery for five months is the fastest way to ruin it. A small smart maintainer (£25–£40) plugged into a 230V hook-up keeps both starter and leisure batteries healthy. If you can't hook up, fit a solar maintenance panel — a 20W trickle does the job.
Fuel: top up, add a stabiliser
A nearly empty diesel tank condenses moisture inside over winter. Fill it to 90%+ before storage. A diesel preservative additive (Wynn's, Forte, Liqui Moly) helps over six-month layups.
Tyres: pressure up, flat-spot prevention
Inflate to maximum sidewall pressure for storage. If possible, move the vehicle one wheel-revolution forward or backward every 4–6 weeks to prevent flat-spotting. Cover the tyres from UV if storing outside.
Damp prevention
Open every cupboard, lift every cushion onto its edge, prop the fridge door open with the catch latch. Pop a dehumidifier inside if storing in a garage, or several large moisture-absorber tubs (Unibond, Vactan) if not. Crack a roof vent on its 'storage' setting.
Monthly winter check (15 minutes)
Walk around the van, glance under it for fresh drips, run the engine for 15 minutes (not just idle — drive it round the block if possible), check tyre pressures, glance at the moisture absorbers, check no rodents have moved in.
Common questions
Should I take the leisure battery out? Only if you can store it indoors at room temperature on a maintainer. In-vehicle with a maintainer is easier and equally effective.
Is starting the engine once a month enough? Better than nothing. A 10-mile drive once a month is far better — circulates oil properly, charges both batteries, dries the brakes.