Winter storage advice

[smorris_12]

Do Not start the car unless absolutely necessary!

Absolutely this bit!

Also, make sure the last run before parking it up gets it properly hot to ensure engine and exhaust are fully dry.

[SSF]

Why would you buy a hardtop convertible and treat it like a ragtop? I drive it the whole winter when I can; I actually prefer it in the winter because it's rwd and fun to drive in the snow.

That's cool - That's how I learned the difference between summer and all-season tires - the hard way ... several of my E46 convertibles I ran all year and they were ragtops. For some of us, these are seasonal cars, not because of any limitation of the E89, just because we have other cars. I use an AWD SUV to deal with Ohio late fall and early winter.... or rainy days... or big flocks of birds....

I have an xDrive 7 series as my people carrier, so if I want safety and comfort - I can use that one in the winter, but the Z4 is definitely more fun to drive (as always). And that's exactly what I bought it for. Especially in fresh snow, with the top down - it's priceless.

Fill the fuel tank as full as possible, trickle charge, handbrake off - Do Not start the car unless absolutely necessary!

I don't know about filling the tank; petrol will degrade quite a lot in the months the car is stored (assuming it's at least 3 months). I'd keep the fuel level low and refill it (from a canister, for example) with fresh one before starting it in the spring.

[ronk]

The tank should be filled to minimise air space in the tank and thus surface area for condensation to form on the tank wall.
The fuel does not degrade enough to notice - I store mine for five months sometimes six using this regime and never had the hint of a hiccup when I start using the car in the springtime.

If you do an internet search, you will see that petrol will last for a year if stored in a sealed container.

Apart from anything else, it’s not going to be cheaper in few months!

[Christopher72]

The tank should be filled to minimise air space in the tank and thus surface area for condensation to form on the tank wall.
The fuel does not degrade enough to notice - I store mine for five months sometimes six using this regime and never had the hint of a hiccup when I start using the car in the springtime.

Never thought of condensation... At any rate, if someone is storing for a year you can add some petrol stabilizer, correctly dosed. We only have about 4+ months of too cold for topless.

[SSF]

If you do an internet search, you will see that petrol will last for a year if stored in a sealed container.

Yes, I've seen this phrase (it usually says "6 months to one year without significant degradation" though). But if you read the next one, you'll see that "However, fuel that is exposed to oxygen, moisture, or contaminants can deteriorate more quickly, resulting in reduced quality, lower octane rating, and increased levels of sediments or sludge." Meaning as soon as it comes out of the pump, it enters in contact with oxygen and moisture and starts degrading. Filling the tank doesn't count as resealing the container.

Now this is not something I'm sure of, it's just what I read on the internet (multiple sources though), but this is how I see the situation.

[ronk]

“Is exposed to” isn’t the the same as “has been exposed to”
That’s how I read it and from experience a six month storage has never been a problem at start up.

I will be filling my tank etc late October and putting it into hibernation and expecting a flawless start up in April as usual

[smorris_12]

Filling the tank doesn't count as resealing the container.

<Sigh> I honestly think the internet will be the end of civilisation.

If you fill the tank you drive out all of the air. There is nothing left for the fuel to interact with, get upset at or diffuse into.

If you don't fill the tank, the petrol will vaporise until it pressurises the tank as far as it can and then stop. Equilibrium is reached. There's a finite amount of oxygen to react with and, when it's done doing that, then stasis is again reached. I don't even think petrol reacts with oxygen, but my chemistry is rusty.

Any which way, and especially for some tiny amount of time which 6 months counts as, nothing is going on.

I actually think that "petrol going off" is a complete myth going back to the days of unsealed tanks or ancient cars that leaked all the vapour out.

I've had cars sat for 18 months and been fine. A neighbour has just dug out his late wife's car that's been sat for 4 years. Again, fired straight up.

[craigdm]

I'm all against car covers these days after using one on my MX5 about 5 years ago.
Flapped around too much and tore itself to bits in the first winter storm.
Not before causing the paintwork to blister on both doors and wings. Quite a common problem when you do some research.