[rvladescu]

Hello I would like to ask your opinion on what to use to protect my BMW 335 e90 body against salt, calcium etc specially the undercarriage. Thank you all in advance.

[Surly73]

Originally Posted by rvladescu

Hello I would like to ask your opinion on what to use to protect my BMW 335 e90 body against salt, calcium etc specially the undercarriage. Thank you all in advance.

I've used Krown Rust Control on other cars with success. The stuff seems to be the best at preventing corrosion but also seems to affect some kinds of rubber in negative ways. Some weather strips seem to expand slightly. Others seem to get sticky until scrubbed down with a rubber/vinyl cleaner. Most seem unaffected.

Be careful, I found out afterwards that the one time I had them do my E39 (when it was about 12 years old) they didn't use the proper lift points and put creases underneath the car. They could have very easily crushed a fuel or brake line. I find this very odd after the owner of the shop came out to talk to me when I was getting a quote, going on and on about how fantastic my E39 looked and how much he loved his E34 etc...etc... Then he should know how to lift a BMW. I DIY virtually everything and in general virtually no one else touches my car. I take wheels/tires for balancing off of the car etc...etc.. and it never seems to fail that the one time I trust someone they screw up. Talk to whoever will be spraying your car and make sure you point out the lift points in the skirts.

Generally on my BMWs I've been doing it myself. First point - it's just as important to clean up after winter as it is to prep for winter. Before and after winter I would unfasten the wheel well liners and mud flaps and clean and protect all of those areas. In the spring I would often put the front and rear (alternatively) up on ramps in my driveway and use a hose-end pesticide sprayer to shoot a Simple Green solution all over the undercarriage and then blast it away. You don't want dried salt/mud mixture hanging around getting moistened every time it rains but now in the heat of summer when the salt really goes to work.

Each fall I would get under the car, remove some plastic and heat shields and get under there with spray cans of Krown T40 or Amsoil Metal Guard HD or Wurth Body Cavity protection spray or Rust Check (green can) and stay on top of things.

You can generally see what areas need protection (seams, welds, bolts, plugs) and how a lot of it is just wasting product and making a mess.

If you have any DIY tendencies and can get under the car this is what I would recommend.

My E39 was driven year round for 14 years and only had very minor issues and only one of the issues was anywhere visible (a "they all do that" minor bubbling around the trunk lock cylinder which I kept on top of with sandpaper, primer and paint). From what I've seen while working on my E90, it's corrosion protection is even better than the E39.

I should also state that I figured out that the seam sealing machine at the factory was malfunctioning the day my E39 went through the production line. A lot of my door seams etc... did not have the seam sealer properly melted into the seams. Instead it was a rectangular ribbon of unmelted sealer on top of the seam and under the paint. Some seams it was partially right, others looked perfect, some were clearly defective. I was outside of the factory warranty period when I put two and two together on this though. If my seams were properly treated everywhere on the car I may have had almost no corrosion issues at all.

[rvladescu]

Originally Posted by Surly73

I've used Krown Rust Control on other cars with success. The stuff seems to be the best at preventing corrosion but also seems to affect some kinds of rubber in negative ways. Some weather strips seem to expand slightly. Others seem to get sticky until scrubbed down with a rubber/vinyl cleaner. Most seem unaffected.

Be careful, I found out afterwards that the one time I had them do my E39 (when it was about 12 years old) they didn't use the proper lift points and put creases underneath the car. They could have very easily crushed a fuel or brake line. I find this very odd after the owner of the shop came out to talk to me when I was getting a quote, going on and on about how fantastic my E39 looked and how much he loved his E34 etc...etc... Then he should know how to lift a BMW. I DIY virtually everything and in general virtually no one else touches my car. I take wheels/tires for balancing off of the car etc...etc.. and it never seems to fail that the one time I trust someone they screw up. Talk to whoever will be spraying your car and make sure you point out the lift points in the skirts.

Generally on my BMWs I've been doing it myself. First point - it's just as important to clean up after winter as it is to prep for winter. Before and after winter I would unfasten the wheel well liners and mud flaps and clean and protect all of those areas. In the spring I would often put the front and rear (alternatively) up on ramps in my driveway and use a hose-end pesticide sprayer to shoot a Simple Green solution all over the undercarriage and then blast it away. You don't want dried salt/mud mixture hanging around getting moistened every time it rains but now in the heat of summer when the salt really goes to work.

Each fall I would get under the car, remove some plastic and heat shields and get under there with spray cans of Krown T40 or Amsoil Metal Guard HD or Wurth Body Cavity protection spray or Rust Check (green can) and stay on top of things.

You can generally see what areas need protection (seams, welds, bolts, plugs) and how a lot of it is just wasting product and making a mess.

If you have any DIY tendencies and can get under the car this is what I would recommend.

My E39 was driven year round for 14 years and only had very minor issues and only one of the issues was anywhere visible (a "they all do that" minor bubbling around the trunk lock cylinder which I kept on top of with sandpaper, primer and paint). From what I've seen while working on my E90, it's corrosion protection is even better than the E39.

I should also state that I figured out that the seam sealing machine at the factory was malfunctioning the day my E39 went through the production line. A lot of my door seams etc... did not have the seam sealer properly melted into the seams. Instead it was a rectangular ribbon of unmelted sealer on top of the seam and under the paint. Some seams it was partially right, others looked perfect, some were clearly defective. I was outside of the factory warranty period when I put two and two together on this though. If my seams were properly treated everywhere on the car I may have had almost no corrosion issues at all.

Waw thank you for taking the time to write to me I appreciate the detail