Viability of keeping a car under a cover for long time?

Just my two cents: if the car is wet then it's going to rust. When it has a cover on, you are keeping the rain off it. I don't see humidity from the ground (assuming this is tarmac, right?) being a huge rust-causing factor because there will always be water and oxygen in the air anyway. Waxoyl won't be a magic seal that stops those two things from touching but does help to lower the chance of water touching it (but note it will still happen). If you are going to put a tarp on, make sure the car is properly dry.

EDIT: Someone please correct me if I am wrong?

It's 100% better off uncovered unless it's got massive leaks somewhere. The cover will only wear the paint. It'll definitely get damp underneath and a waterproof tarp will hold this against the paint and make it bloom and blister.
Make sure it's kept dry inside - Air it out whenever you can, otherwise it'll go mouldy.

i wouldnt cover it , wash and wax it as often as you can , open the windows /boot on a fine dry day to air the car

cars don't melt away when sat outside ...it'l be fine if you check over it once in a while

I actually bought one of these "quadruple" layer breathable covers that claim to be largely weather resistant but not 100% waterproof (I think it's around 80%).



Sadly my car seals have long gone. I actually use another cheaper Halfords breathable cover on top of the car-fitting cover when it is predicted to rain - this way, the least amount of water goes through, and I can take the second cover off on a nicer day.


But you're right - how much moisture do these covers get rid of ? And would a tarp draped over it have any effect? I would like to construct something but space is very tight - sorry! EDIT: I just re-read what you said. This actually isn't such a bad idea ... I'll look into it. 

I'm just wondering without buying a moisture indicator what homemade tests can be done for moisture? 

In regards to what car : typical non rust-proofed Jag. 

Even with the mega expensive all climate weatherproof breathable covers they state to remove them once a week to air the car and let the trapped moisture to dry out.

If it runs and you can move it, I'd run the engine up to temperature, give the inside a warm up, using air con if it has it and shunt it back and forth, using the gears every so often.

Ditto with the wash and wax, but rather than waxing everytime, use a spray on, wipe off wax for speed.

I usually use Sonax Brilliant Shine Detailer, which, even as a wipe on, wipe off product beads water from the bodywork for longer than wax. Just ordered 5 litres for 32 quid from Amazon.

Covers are for keeping the dust off (in my opinion) when kept in doors/ in a garage.

Paint is for protecting the metal from rusting. Wax is to protect the paint.


They do more damage than good in the long term when covered outside.

My car has lived by the sea (I can hear the waves right now I'm that close) and parked on the road.

Salty air is a killer but It's not rusted away. It's had since the 90s to do so and it hasn't. I'm guessing that's because the air keeps it dry and there's nothing trapping in the moisture.

If it was cocooned in a cover it would probably bubble up in rust in no time.

Do you know where it's coming in Seb?
If it's windscreen seals go round with a tube of black sealant and fill any splits in the seals.
A waterproof half cover might be an idea,a halfway house that would at least stop rain coming in through the screen.

This might help you too,check the scuttle drains !
www.jec.org.uk/forums/viewtopic.php?f=39&t=1921

Good luck,the drains come out in the wheel well from what i can see with a right angle at the end which is probably where the blockage happens.

The drains underneath the chrome trim on the windscreen pillars seems to be a common culprit too.

WATER LEAKS -- A-PILLAR DRAIN: At the corners where the rain gutters meet the windshield, the seal appears to have a gap underneath the chrome trim. This is deliberate, providing a drain for this area of the roof down the inside of the A pillar. It'd be a bad idea to try to seal it up.

Pat Johnson was getting rainwater on the floor, and finally figured out it was coming from these drains at the top front corners of the roof. Water that finds its way into these drains -- a goodly amount, to be sure -- is supposed to run down the pillar between the chrome trim piece and the structure and through the bodywork in front of the door. Somehow, it was being diverted inside the structure, and ended up in the carpet instead. The solution involved removing the chrome trim piece covering the A-pillar. "Being a novice at this, I was a little (a lot) scared to start removing rivets. They look so permanent! But I bit the bullet and started drilling. It was easy! I found gaps between the body and the molding. After calling a glass repair shop and getting some silicone, I went to work. I filled all the crevices and opened the drain hole. I then refit the chrome and put my first rivets in. I must say, I think I did a pretty good job. It looks just like new and the lake is gone.

"It is supposed to drain in front of the door. Leaves and some other unidentifiable gunk were plugging it. The channel was also narrower than I think it was supposed to be due to the black rubber material under the chrome spreading toward the center."

Harry Trafford elaborates: "After drilling out the little pop rivets, carefully pry the chrome off. It will come off. I used a small stiff detailing brush to clean it all up under there. I took a very small screwdriver and ran the blade under the gasket edges to clean them out. A lot of dirt was removed. I purchased a tube of Permatex Auto Glass Sealer, then using the screwdriver end, I gently lifted the gasket edges, sliding the tip down the glass and followed right behind it with the sealer. The sealer is thin and is supposed to run into the crevice. If you get the sealer smeared all over, use acetone or nail polish remover to clean it up. Do not get acetone or nail polish remover on the car's paint!

"I used small 1/4" to 3/8" sheet metal screws to reattach the chrome strips on the "A" pillar. Works fine."

Note that, as opposed to Johnson's '89, the chrome trim on the A-pillars of the author's '83 are held on with Phillips screws instead of rivets. Or, maybe somebody like Harry has already had it off!