[Grady Clay]

When stored in an un-heated space, critical is the temperature variation and the ‘mean temperature’.

If the variation is around freezing or the dew point, this is very bad, even in a relatively dry climate. The combination of a cold car and warm(er) and more humid air lead to condensation (& frost) inside cold ’closed’ spaces. Like cars, instruments, engines & transmissions. Wide temperature variation exacerbates the situation.

This is caused by two factors; changes in temperature and changes in atmospheric pressure. The temperature usually changes daily (day-to-night) and the barometer on a 3-day (sorta) cycle. Every time the environment temperature goes up or the atmospheric pressure goes up, air and any moisture is forced into any space not hermetically sealed. Cold surfaces condense the moisture (to liquid or frost) and damage is done.

What to do?

Keep the temperature constant. Prevent variations around the dew point. A well insulated space with lots of ‘thermal mass’ and very low humidity works well. There are mechanical de-humidifiers designed to operate in below-freezing conditions. 55-gallon drums of water (with anti-freeze) work well for ‘thermal mass’. Most plastic barrels won’t leak if frozen.

Some use a de-humidified ‘tent’ (big Ziploc) inside a garage. This has the advantage of preventing moisture intrusion and the mechanical dehumidifier provides some heat.

I agree about rodents. Good ‘snap-traps’ work well if attended to daily. A few desiccated corpses tend to discourage others.

Depending on where you live in Western Montana, you can actually drive your 911 in winter. Find snowed over (or dry) roads that do not have applications of Magnesium Chloride. Nice ol’ snow melts and evaporates without harm. The key is a reasonable and ‘aggressive’ drive to get everything up to temperature. That includes engine, transmission, brakes, clutch and more. A periodic stint at dry 80F inside also helps. The 911 doesn’t like to sit – it is a ‘runner’. This athlete needs weekly exercise. If that isn’t possible, then a good strenuous ‘work-out’ when possible is best. Never start without hard running.

All this leads in to the type of ‘winter preparation’ done. Some preparation is designed for years (or decades) of storage. That long of storage usually requires significant rebuilding of systems.

We are considering storage prep that still allows use when the conditions allow. Clearly fresh (dry & clean) oil is high on the list. To my mind, fuel is critical. Pump gasoline has a short ‘shelf life’. Stabil helps. You might consider unleaded 100 octane aviation fuel. It is designed to sit for long periods and then perform to high level.

I use always dry Nitrogen in my tires. The key here is to not have any moisture in the tires. Condensation to liquid water or frost to water ice can be a big issue. Some tires can loose bead seal at very low temperatures (my Michelin steel tow-truck tires go flat at about -30F if not at 110 psi). Set yours at the high end of specification and then bleed down to drive.

When you drive your 911 in winter, try and drive fast, high power (and uphill) as you go to storage. Park it HOT.


I’ll encourage you to search all the threads (Pelican & other) on this subject and post the links. A good project can be to compile ALL the suggestions and offer them for comment. There are lots of skills here. The issues are for 911s not regularly driven, ones for winter storage and the occasional decade storage. There are differences among 911 models. Each situation is different and there are many variations in between and depending on environment.

Best,
Grady