Proper care of original paint and fixing small rust bits - W115

[cleeves]

Hello,

I live in the city in Atlanta and I have a 1976 W115 300D shown below.





It's all original, 1 owner, and the paint is very good, and I think everything works except the vacuum locks. It's nearly rust-free and I've had it for a year. I barely drive the car, but I don't have a garage for it as I live in the city. So, it doesn't and won't see any salt, but Atlanta isn't a very dry place. I really want to take as many steps as I can to preserve the car given these circumstances. The trunk and floors are not rusty. I've done seemingly countless other repairs on it too in the past year with 100% genuine MB parts, including:

rebuilt/balanced injectors
replaced vacuum pump
replaced all rubber fuel lines
completely overhauled the brake system-new rotors, calipers, pads, and hoses.
replaced windshield seal
replaced tail light gaskets


1. General paint care. Having taken it to the automatic carwash/wax a handful of times over the last year, I've noticed these dripping streaks of a lighter color on the paint. I've scrubbed them with a clean t-shirt and soap but they don't seem to be coming out. I noticed this a couple times in the carwash but the car came out with them dry, so it's something that apparently happened rapidly during the carwash. Maybe it's just wax from the automatic wash and I didn't scrub hard enough? Has some chemical in the carwash started to deteriorate my paint because it's really old? The fenders all have these drips on them.



2. Repairing rust under trunk seal. My trunk has been leaky (but not yet rusty), so I have taken the following steps to fix it so far. First, I replaced the tail light seals. Then, I removed the trunk seal and used weather stripping remover to get the old glue out. Went alright, but I found a bit of rust on the passenger side. I used a dremel and ground it all out, and a small part of it went all the way though. See hole on the left in picture. Next, I put on a coat of Ospho 605 metal treatment and let it dry over night. Then I used a small brush and applied touch-up paint. This dried for 2 days, and then it rained. I was going to put in the new trunk seal today, and I noticed my touch-up paint was already flaking off! See flake off on right side of picture. If it flakes off after 1 rain, you bet it's going to rust right through in no time.


What happened here? Why didn't the Ospho work? I've bought some POR-15 to use instead it it will arrive next week. Either way, I'm frustrated.

How many years will the car last outside being that it's not garaged? Many trim pieces have aging plastic/rubber that is hard or warped and it's simply too much to replace everything given the value of the car. Given this, I can't imagine it will stay rust-free as long as a brand new car would have back in 1976.

[cleeves]

More importantly for part 1 above, how bad is it to use the automatic car wash? Will it cause significant premature wear on the paint?

Looking for general tips on caring for 42 year old paint...

H

[JMela]

Pretty car.

I'd avoid machine washes and maybe try to find a garage to store your car, at least an off-street lot. Get some 5 gal buckets and wash it yourself.

Streaking might have to do with air pollution or maybe soapy car cooking in hot sun? Try 'claying' these problem areas and see if that helps.

Tons of car detailing youtube vids and forums out there. I think MB was still using single-stage paint on these but am not 100%.

[Mike D]

All /Eights were originally base/clear to my knowledge. I've never seen one which wasn't. My knowledge is limited to the cars I have seen in the U.S.. Models produced for other markets might vary.

Use the "two bucket" system for washing. "Dawn" dish soap. Invest in a , car washing sponge, soft bristled brush, good clay bar, a "shammy" (Chamois wiping cloth) and a supply of microfiber cloths.

Your paint appears to be in decent shape. Minimize the use of any harsh abrasives. Use the clay bar sparingly.

[Shortsguy1]

The phosphoric acid only does its magic when you apply it to rust (I think). If you ground away all of the rust, I don't ospho has any value/use at that point. Also, I don't believe touch up paint will attach to the phosphoric acid residue, unless the ospho reacted with actual rust to create iron phosphate. I would imagine a primer coat of paint is necessary even then.

POR is a good option below the rubber trunk seal. Just don't get it where it will be seen. And use thin coats. It does some weird bubbling thing if you apply it too thick.

My 1968 220D /8 has single stage paint. I mean, I am not a paint expert, but I have used Meguiar's Ultimate Compound in one or two places to remove the top layer of oxidized paint, and I just don't think that would be possible if it had clearcoat.

[Rick76]

In 76 only metallics had clear coat.

[Mike D]

Yup, Rick's right. Forgot about the non-metallic colors.

[cleeves]

Appreciate the input.

Originally Posted by JMela

Pretty car.

I'd avoid machine washes and maybe try to find a garage to store your car, at least an off-street lot. Get some 5 gal buckets and wash it yourself.

Streaking might have to do with air pollution or maybe soapy car cooking in hot sun? Try 'claying' these problem areas and see if that helps.

Tons of car detailing youtube vids and forums out there. I think MB was still using single-stage paint on these but am not 100%.

I don't think it's air pollution, as it was dry immediately after getting out of the carwash. I'll look into the claying and check out more videos/sources. I'm pretty sure it was a single stage paint. I'd like to cover it more, but given that we get groceries (thats the biggest use) once a week, it's just not practical to cover it unless we go out of town. I've got off-street parking, and it's shaded. However, the giant tree overhead drops this oily substance for about half of the year. I also wonder what this does to the paint.... suppose if there is a good coat of wax it's ok? Garage parking is highly impractical here, would require a 3 block walk to a parking garage and paying at least 100 bucks a month. Sometimes I feel we shouldn't have gotten the car, but my partner really wanted it....

Originally Posted by Shortsguy1

The phosphoric acid only does its magic when you apply it to rust (I think). If you ground away all of the rust, I don't ospho has any value/use at that point. Also, I don't believe touch up paint will attach to the phosphoric acid residue, unless the ospho reacted with actual rust to create iron phosphate. I would imagine a primer coat of paint is necessary even then.

POR is a good option below the rubber trunk seal. Just don't get it where it will be seen. And use thin coats. It does some weird bubbling thing if you apply it too thick.

My 1968 220D /8 has single stage paint. I mean, I am not a paint expert, but I have used Meguiar's Ultimate Compound in one or two places to remove the top layer of oxidized paint, and I just don't think that would be possible if it had clearcoat.

That makes more sense regarding the Ospho. I'll apply the POR below the trunk seal. I got the clear stuff. I guess it's OK to apply this to bare metal (non rusted) ? Or would the proper primer hold better?

It's a single stage paint over primer. No clear coat.

The outer body of the car has a few rust sports, about 1/8" in diameter, with two 1/4" diameter. They have grown slightly in the last year, so I need to fix them. I was consider for these to put a tiny dot of POR on, then touch up paint? Thoughts on this?

Warmth,

Henry C.

[Benz Dr.]

Why don't you get a car cover?

[cleeves]

Originally Posted by Benz Dr.

Why don't you get a car cover?

Well, I've got a car cover. But it's just annoying to have to cover and uncover it every week when we go out. It's my partner's car, sometimes she takes it out during the week (so maybe 1-2 drives per week) and it would be an inconvenience to her, too. I guess we could consider this, but I'd just have to be convinced it's worth that effort.

H

[Mike D]

How did you get JMela's and my post blended?

I must admit to being a bit baffled. You say you don't want the hassle of removing a car cover but you are concerned about the paint? It's a heck of a lot easier to slip a cover off and on than it is to wash your car weekly.

Me? I'd go with monthly washes, car cover and a California Duster for the in-between drives.

[cleeves]

Originally Posted by Mike D

How did you get JMela's and my post blended?

I must admit to being a bit baffled. You say you don't want the hassle of removing a car cover but you are concerned about the paint? It's a heck of a lot easier to slip a cover off and on than it is to wash your car weekly.

Me? I'd go with monthly washes, car cover and a California Duster for the in-between drives.

Oh dear! The post is fixed now. The "quote +" tag wasn't showing up on my computer for some reason, so I coded it in myself and inadvertently used your name by mistake.

I wasn't washing it weekly. Like maybe every 2-3 months. It's easier to do an automatic car wash every 2 months than uncovering it and recovering 6 times per month.

I originally wanted a driver and not a show car, but ended up with a near-show car and now I feel compelled to keep it that way. I guess when I bought it I just figured as long as there was no salt and I parked in the shade I'd be OK, but now I'm not so convinced. My thread was more about a 1-year evaluation of this notion, and consult the opinions of others to decide about changing this course of action. I'm now closer to being convinced that covering it during the week is the way to go.

H

[Benz Dr.]

A car cover is the way to go. It will protect the paint and the interior of your car. 100 bucks should get you a decent one.

[280EZRider]

I agree that the paint is definitely single stage. Even the W123s with non-metallic paint have single stage. Wash and dry the car yourself (car washes are the kiss of death) and most of the time you don´t need any soap at all. That Dawn soap is OK for removing tree sap, but it´s best to avoid parking under trees and to use shades to protect the dash and rear carriage shelf.

For me, (best option) walking 3 blocks to a $100 per month garage is nothing but I´m just a kid at 71, so what do I know? If you decide to use a car cover, make sure it´s breathable, especially in the humidity of Atlanta.

[cleeves]

Originally Posted by 280EZRider

I agree that the paint is definitely single stage. Even the W123s with non-metallic paint have single stage. Wash and dry the car yourself (car washes are the kiss of death) and most of the time you don´t need any soap at all. That Dawn soap is OK for removing tree sap, but it´s best to avoid parking under trees and to use shades to protect the dash and rear carriage shelf.

For me, (best option) walking 3 blocks to a $100 per month garage is nothing but I´m just a kid at 71, so what do I know? If you decide to use a car cover, make sure it´s breathable, especially in the humidity of Atlanta.

One thing I like about single stage was I think it would be easy for a shop to blend if there was any issue. I used to have a clear-coat car, it flaked something terrible!

I spent 3 hours detailing the car today. It looks terrific except I couldn't get off all those light colored drips. Maybe I'll try a clay bar at some point. I'll not use the automatic wash again. It's now safely under cover (breathable cover) and we plan to keep it this way at all times while not driving it.

Thanks for all the input, everyone. I will have some questions about the rust removal from prior posts. Of note, I'm still wondering if POR-15 will hold to bare metal as a primer.