Driving a Triumph Stag through the winter

The decision itself

Two things are true at once, and neither cancels the other. A car that is used stays healthier than one that sits: seals and hoses stay wet and supple, brakes stay free rather than corroding to their discs, the battery lives at charge, and the engine reaches full operating temperature regularly, which is the only thing that boils the moisture and fuel dilution out of the oil. A car laid up all winter needs recommissioning for a reason.

The other truth is that a car which meets road salt corrodes, and the Stag is a steel-bodied car from the 1970s, built before rustproofing was taken seriously. Every salted drive puts the most destructive substance the body will ever meet into its sills, seams, arches and box sections, and that damage is cumulative and largely invisible until it is expensive.

This page does not tell you which way to jump. It sets out what winter use costs the car and what it gives back, so the decision is yours, made with both halves of the picture in view. If you would rather not face the choice at all, the storage and lay-up guide covers the alternative properly.

Salt matters more than any product

Washing the underside after every salted drive is the single most effective thing a winter owner can do, and it is the thing most people skip, because it is cold, wet and unrewarding. Nothing you can spray on the car outweighs it.

The reason is chemistry rather than tidiness. Dry salt sits on metal doing very little. Salt in solution is an electrolyte, and it accelerates the corrosion of steel sharply. Worse, salt residue is hygroscopic: it pulls moisture out of the air, so a salted seam stays damp and keeps working long after the car looks dry. A car put away wet and salted after a drive is worse off than one left standing out in the rain, because rain is relatively clean water and a garage holds the damp salt against the metal.

Getting water underneath properly means more than a quick pass over the visible sills. The salt sits in the wheel arches, on the tops of box sections, along the floors and around the suspension mountings, so the water has to reach those places. A hose with an underbody lance, or a wash that lets you work along the car at ground level, does the job. Be careful with a jet wash: used close up it can drive water past seals and into cavities you would rather it did not reach, and it will strip underbody protection off the very areas you are trying to save. Rinsing is the aim, not blasting.

Where the water lands, the rust follows, so it is worth knowing where the Stag is weakest before winter starts. The bodywork and rust page maps the sills, arches, screen surround and suspension mountings that winter is attacking.

The Stag specifically

The hard top is the winter answer

The Stag was sold with a hard top for a reason. Fitted in autumn and left on until spring, it turns the car into a usable coupe: warmer, quieter, draught-free, and kinder to a hood that would otherwise spend the season wet. The fittings, the two-person lift and the storage of the soft top are covered on the soft top and hard top page rather than repeated here.

Cooling cuts both ways in winter

This car's reputation is for running hot, which makes the winter failure mode easy to miss: a Stag can also run too cool. A thermostat that is stuck open, or one that has been removed and never replaced, means an engine that never reaches proper operating temperature on a cold day. That is genuinely bad for it. A cold-running engine wears faster because its clearances and its oil are designed around operating temperature, and moisture and unburnt fuel condense into the oil on short cold runs instead of being boiled off, diluting it and attacking bearings. The gauge sitting stubbornly low on a winter run is not a sign of a healthy cooling system. It is a fault worth fixing.

Antifreeze is not optional

On this engine antifreeze does two jobs, and freezing is only the smaller one. The corrosion inhibitors in it protect the aluminium heads against the iron block, and those inhibitors wear out with time even though the antifreeze itself still prevents freezing. Old antifreeze that passes a frost test may have lost the protection the heads depend on. The correct type and strength for your car, and the renewal interval, come from the workshop manual or the Stag Owners Club rather than from memory. Why the mixed-metal engine depends on this is explained on the overheating page.

Know what winter is attacking

The Stag's corrosion map is specific: outer sills, wheel arches, the windscreen surround and scuttle, the floors and footwells, and the rear suspension mountings, among others. An owner who knows the list can inspect the right places in autumn and again in spring, and can aim the wash at the right spots after a salted run. The full map is on the bodywork and rust page.

Underbody protection, without the sales pitch

The products on offer divide into three broad types, and they differ in principle rather than merely in branding.

• Wax-based coatings, such as Waxoyl and Dinitrol. These are sprayed or brushed on and set to a firm or semi-firm film. The thinner cavity versions are made to creep into seams and box sections before setting; the heavier underbody versions form a tougher skin that resists abrasion. Because they set, they stay put, but a hard film can crack or be breached, and corrosion can then work underneath it unseen.
• Lanolin-based products, such as Lanoguard. These stay soft rather than setting, which means they self-heal over small scratches and keep creeping into gaps after application. The softness that gives that behaviour also means they wash off and wear more readily, so they ask for regular inspection and topping up.
• Oil-based products, such as Fluid Film. These creep furthest and displace moisture actively, which makes them good inside cavities and seams. They do not set at all, so they migrate and thin over time and need the most frequent reapplication of the three.

Now the part nobody selling these products says. There is no independent comparative testing of these products worth citing. The advocates of each are sincere, and most are reporting what genuinely worked on their own car, in their own climate, on their own preparation. Much of what is written online about them is written by people selling something. This archive has no commercial interest in any of these products, and it cannot tell you which is best, because nobody honestly can.

What can be said plainly is this: preparation decides the outcome more than the brand does. Any of them applied over existing rust and trapped dirt seals the problem in rather than out, and any of them needs cleaning, drying and reapplication on whatever schedule the product's own instructions give. Coverage, drying time and reapplication intervals come from the maker's instructions, not from this page.

The practical side

Demisting a car of this age

A misting screen is a safety problem before it is a comfort one. The Stag's heater is capable once the engine is warm, but it asks for help: clean glass on the inside, since the film that builds on old glass is what condensation grips, dry carpets and mats, since a wet interior feeds the screen all journey, and sound heater hoses, valves and seals so the heat and the airflow actually arrive. A car that mists heavily on damp days is often telling you about a water leak or a failing heater rather than about the weather.

Wipers and washers

Wiper blades that were adequate in summer drizzle will not cope with winter spray off a wet road. Fit fresh blades in autumn and check the washers actually deliver to the screen rather than dribbling. Washer fluid needs an additive against freezing; plain water in the reservoir freezes on the first cold night, and the correct concentration is on the bottle rather than here.

Tyres in the cold

Cold rubber grips less, and old rubber grips less still. A car brought out in autumn may be sitting on tyres that have hardened with age, which feel acceptable in the dry and are treacherous on a cold, greasy road. Check the date codes, the tread and the pressures, remembering that pressures fall with the temperature. The wheels and tyres page covers date codes and the factory pressures.

Lights

Winter means driving in the dark and being seen in the murk, and 1970s headlamps are modest at the best of times. Clean lenses, correct aim and every lamp working are the baseline. Dim lights on a Stag are frequently an earth or connector problem rather than a lamp problem, and the electrical page covers where to look.

The battery

Winter use often means short, frequent runs, which is the pattern that kills a battery: every start takes out more than a brief journey puts back, and the cold reduces what the battery can deliver while the engine demands more of it. A battery in rude health copes; a marginal one picks the coldest morning to fail. If the car's use is mostly short hops, an intelligent conditioner between runs keeps the battery honest.

Carry what you would need if it stopped

A breakdown that is an inconvenience in July is a different matter on a dark January evening. A warm coat, a torch, a charged phone, a warning triangle and the recovery number are the minimum. The before a long run checklist covers the spares worth carrying year-round.

When not to go out

Ice is the plain one: a Stag on period-style tyres with no driver aids is not the car for an icy morning, whatever your confidence. Standing water is the subtler one, because it hides depth, and because drowned electrics and a soaked interior follow a misjudged ford. The day after the gritters have been through deserves its own mention: the roads are dry and inviting, and every surface is carrying a fresh film of dissolved salt. That is the day the underside wash matters most, or the day to take a different car.

There is no shame in leaving it in the garage. The car will be there in spring, which is more than can be said for one backed into a hedge on black ice or quietly rotting from a winter of unwashed salt.