So why can they build a 300K engine, but paint that only lasts 15-20?

General conversations about BMW E28s and the people who own them.
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Mike W.
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Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

So why can they build a 300K engine, but paint that only lasts 15-20?

Post by Mike W. »

Mostly rhetorical, but still a question, why is it they can build a 300K engine, such as M20, M30, M5X and even some Japanese such as Toyota, but struggle with making paint last 15 years. Well, mostly clearcoat, but it's still paint. I mean engines have to deal with incredible mechanical stresses, thermal stresses, constant inhalation of a chemical soup (gasoline) along with who knows how many tons of dirty air, all sorts of abuse with an assortment of metals sliding back and forth on each other with (hopefully) a thin layer of oil inbetween, and my calcs suggest something along the lines of 900 million revolutions for 300K. Yet let paint out in the sun for 15-20 years and it just goes to hell. BMW does better than average from what I see, but not that much better. Seems an expensive car will not necessarily have longer lasting paint, but a cheaper car will have shorter paint life.

I bet here in California the most common causes of E28s for instance to be junked, in order, were

Emissions, failing a smog test
Paint, clearcoat failing
Automatic transmission failure
Overall wear and tear, inside and out
Engine failure.

Now, not much I can do except rant and rave, which incidentally I'm very good at, or pay tons of money for a paint job. Seems like the cheap places like Earl Schieb are now gone, and to me they did provide a good service even if it was a cheap paint job, it was still a new paint job. And it also seems most body shops really only want to do collision repair on late model cars.

All of which I suppose is a long way of saying all 3 of my cars now have failing clearcoat. The wife's touring is the only one of the 3 that I really have much interest in doing much with, but still, it's frustrating. Exasperating. And more.
Galahad
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Re: So why can they build a 300K engine, but paint that only lasts 15-20?

Post by Galahad »

I think part of the issue may be that you need some sort of UV protection (which gets burnt off) and there's only so much paint you can put on a car. Additionally, getting an engine to 300k requires a lot of maintenance - same thing can be said of paint, but I know far fewer people that take good care of their paint than their engine.

I'm planning on wrapping my nice car this summer in an attempt to avoid burnt paint down the line (and learn something in the process).
gadget73
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Re: So why can they build a 300K engine, but paint that only lasts 15-20?

Post by gadget73 »

I have something I'd like painted. Its been at least partially re-painted and thats failing at this point. Unfortunately it will cost more than the car is worth to have done, so I'm in that limbo area of do I just let it ride or dump buckets of money into it.
Shawn D.
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Beamter
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Re: So why can they build a 300K engine, but paint that only lasts 15-20?

Post by Shawn D. »

They can make paint last far longer, but it wouldn't be something you'd necessarily want to look at. You could paint your car with moisture-cure urethane made for bridges, for example.
1st 5er
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Re: So why can they build a 300K engine, but paint that only lasts 15-20?

Post by 1st 5er »

Simple answer, climate change. :laugh:
WilNJ
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Re: So why can they build a 300K engine, but paint that only lasts 15-20?

Post by WilNJ »

Galahad wrote: Mar 16, 2023 12:51 AMAdditionally, getting an engine to 300k requires a lot of maintenance - same thing can be said of paint, but I know far fewer people that take good care of their paint than their engine.
^^^^ This.
gadget73
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Re: So why can they build a 300K engine, but paint that only lasts 15-20?

Post by gadget73 »

engines aren't affected by the sun, paint is. Park inside and drive only at night and with even basic maintenance your paint will last a whole lot longer. Unless you want to rearrange your life around avoiding the daystar just so your paint lasts longer though I suspect that solution isn't going to catch on.
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