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Winter storage


11 Jan 2021
What with the values of 997s rising as they are, I've decided to store my car on Thursday for the next 6 months - don't want to accumulate mileage on routine trips or expose it to the winter weather anymore. Cayenne or Defender can carry out cold-weather duty!

Does anyone have tips for storage? It will be in a heated garage under an indoor car cover. Do I need to disconnect the battery as there is not a plug socket I can constantly use? CS Free charger perhaps? How often should I start it up, roll the tyres etc? Anything else?

I also take mine off the road through the winter and would suggest the following:

1: Ideally an Oil/filter change before storage - takes any contaminants out of the engine and prevents them becoming acidic.
2: Check your coolant and washer fluid strength will be sufficient for any cold weather.
3: Fill the fuel tank to maximum, with a good quality Super Unleaded (I believe Esso Synergy Supreme+ has no Ethanol content) - this prevents condensation putting water into your fuel over the cold winter months.
4: Optional: Add a fuel stabiliser - there's one available from Porsche Classic, other brands are available.
5: Hold the wipers off the screen by placing something under the wiper arms, I use a short length of foam pipe lagging. The idea is to prevent your wiper blades from distorting whilst stationary - often the cause of subsequent wiper judder on stored vehicles.
6: Pump up the tyres to maximum pressure.
7: Put the car on tyre savers OR use thick carpet pads under the tyres (to prevent them flat spotting).
8: Place bags of Silica Dessicant inside the footwells, to prevent condensation - you can buy them off eBay.
9: If you live in/near the countryside or have mice/rats locally: Place rat traps around the garage and bung your exhausts up with wire wool.
10: Cover with a breathable car cover.

Some people recommend starting and running the engine until thoroughly hot (c110 Deg Oil temp) every few months but unless it's a dry winter's day that might cause more problems with condensate in the engine/exhaust, so others tend to leave it entirely over the winter.

I can't comment on the battery situation because I'm able to leave mine connected to a CTek charger but if your car has a Tracker, then bear in mind that without the main vehicle battery, the Tracker will use up its own and require replacement - just something to consider.

Hope that helps.
Alternatively just:

- pump tyres up c2-4 PSI over recommended pressure

- disconnect the battery or put on a conditioner

- put plenty of mouse traps down even if you've never seen mice before!

nb I disconnect the battery but you have to be careful if your Insurance requires the car to be alarmed. I use a solar conditioner for my boxster as its stood for weeks without being used and its easier for me with a solar charger than a mains powered one. Its worked great to keep car battery topped up......I've seen people fit them to garages without power ie fit the solar panel outside and run a cable to the car inside.

ps thats all you need for a car stored for up to 6 months, if your storing for years its different. I would not start or move the car at all unless your actually going to be driving it properly.

You can also leave the hand brake off if safe to do so and leave interior vents open / put in a dehumidifer bag if the garage is damp but if yours is heated it should not be a problem.....

and don't worry about it, your not going to damage a car not moving it for 6 months, main issue is the battery ;-)
That's a pretty comprehensive list! It never occured to me that a mouse might want to head up an exhaust pipe, but you never know. :eek:
Its the wiring looms not the exhaust that you want to worry about......for a few £ plenty of mouse traps is a no brainer :thumb:
Comprehensive replies indeed, thanks. I didn't put it into storage yesterday as it was raining and I want to put it away dry.

The car has only just been serviced so all fluids and filters are new. Will fill up with Optimax on the way back from the car wash.

Didn't think to put something over the exhausts - good call. It's a communal garage so does get some daily traffic but that probably doesn't put the mice off!
Good luck to any mice that go up the exhaust. I think the air box would suit them better.
Out of interest - anyone using a sensibly priced cover for a car in a garage (basically reduce dust etc)
I'm using the cheapest breathable cover I could find as it won't move as the car is inside - just to offer some protection from dust. The outdoor covers need to be good quality as the wind moves the covers around and when dust gets underneath this scratches the paint.
The car is now tucked away for winter. Disconnected the battery but realised I had to leave the bonnet slightly open so I can get back in again to reconnect it, not much I can do about that I guess but I don't like leaving it open.

Noticed the existing battery might be on the way out (sluggish on turnover). What are the recommended batteries for 997s these days?
I've been storing my 997 over winter for the last 6 years (owned 10) and the above is all great guidance. Not had any issues so far.

My old Exide battery survived 7 years on the regime above. But I felt it was time for it to go when, even fully charged up, it didn't activate PASM properly once (ie: defaulted to Sport).

So I did some research and bought:

Varta F18 Silver Dynamic Car Battery: Type 110 - 585 200 080 - 12V - 85Ah - 800CCA - L315 x W175 x H175mm

When shopping watch out for dimensions as some sites offer both 175 and 195 cm height. Not sure if the 195 fits, the Exide I had in before was 175 so I went for that.

This is the identical same battery as the Bosch S5 (same factory) but costs £10 less. Paid £89 in postage (from battery megastore) which I thought was a bargain.

Btw, suggest placing a rag or locking the latch mechanism to shut so as to avoid any accidental closing of the bonnet and associated world of pain.
A fella told me that the electric motors in the windows, seats, HVAC etc can benefit from regular exercise, even if you don't need to actually start the car.

One of my dads old cars suffered a seized clutch too... as a result I get in and dip the clutch a few times on a regular basis during a prolonged lay-up.

I don't generally mothball the car over the winter, as I enjoy drives on dry days. Certainly avoid wet salty roads though.
On a similar vane, leave the hand brake off as that is very likely to seize on over time.
If it's a heated garage then you might be able to get away with a compressor type dehumidifier which are relatively inexpensive to run. My garage is both heated and dehumidified down to 55%RH. Desiccant types are significantly more expensive to run as they use a heating element but will still work in very cold conditions.

I plumbed a rad and plinth heater into the garage last year so sold the desiccant.

Corrosion pretty much stops at anything below 60%RH. My Nobles discs were rust free after the 6 month winter lay up last year.

The 911 has PCCB's so not an issue anymore, but still good to know that my set up works as intended. :)
ohms777 said:
Corrosion pretty much stops at anything below 60%RH. My Nobles discs were rust free after the 6 month winter lay up last year.

That's good to know; I just checked and we are only at 30% humidity (and it's a pretty drizzly day).

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