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Discussion Starter #1
Guys,

A bit of a devil's advocate question here: what is the benefit of spending more for a low-mileage car if the rubber is old?

Here is what I mean: the newest of these cars is now 14 years old. Even with very low mileage (<50k), it seems as though their oil pan gaskets will leak, their rear differential seals will leak, control arm bushings will need replacing, motor/tranny mounts may also have gone bad, shifter bushings may also be rotted, etc. Jack Baruth recently wrote an article for R/T in which he argued that old rubber, essentially, throughout the car makes even low-mileage, nice-condition old German cars not as awesome to drive now as they were new.

I understand that some things inexorably wear with mileage--caramel seats and rod bearings in particular come to mind.

What is the benefit, if any, of paying a significant premium for a low-miles car versus one with higher mileage that has had a lot of these items replaced along the way? I'm thinking of a 50k, bone-stock, all-original car compared with a 150k car that's had a lot of wear items replaced along the way. Thoughts?
 

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Guys,

A bit of a devil's advocate question here: what is the benefit of spending more for a low-mileage car if the rubber is old?

Here is what I mean: the newest of these cars is now 14 years old. Even with very low mileage (<50k), it seems as though their oil pan gaskets will leak, their rear differential seals will leak, control arm bushings will need replacing, motor/tranny mounts may also have gone bad, shifter bushings may also be rotted, etc. Jack Baruth recently wrote an article for R/T in which he argued that old rubber, essentially, throughout the car makes even low-mileage, nice-condition old German cars not as awesome to drive now as they were new.

I understand that some things inexorably wear with mileage--caramel seats and rod bearings in particular come to mind.

What is the benefit, if any, of paying a significant premium for a low-miles car versus one with higher mileage that has had a lot of these items replaced along the way? I'm thinking of a 50k, bone-stock, all-original car compared with a 150k car that's had a lot of wear items replaced along the way. Thoughts?
Well, it depends on what you want the car for. Is it something you plan to stick in a garage for 20 years or do you want to drive it? If it's the latter, I recommend finding the healthiest example in your budget. When I was shopping for mine, I had a budget in mind and wanted to stay under 150K miles. I found my car for sale at a new BMW dealer and it had a lot of wear items replaced, such as brakes, belts, and clutch. It also had new headlight adjusters installed as well as a new rearview mirror. Body is straight except for a small depression on the rear of the trunk. It did have some paint work and the bumpers were resprayed. This is what I'd consider normal for a 136,xxx mile car. Best of luck in your hunt!
 

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Even a 0-mile beast will need maintenance at this point. The benefit is peace of mind that the engine internals are all healthy (or healthier), which definitely has a benefit. But a 50k beast that saw 8x track days a year with questionable maintenance vs a well-maintained 150k that was just driven back-and-forth across the country...i'd take the 150k.
 

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Discussion Starter #4
Track time, sure. I'm more trying to compare an enthusiast-owned, well-maintained, but high-mileage car versus a low-mileage car that simply wasn't driven a lot and got annual oil changes with not much else.
 

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Thermo-oxidative rubber aging is highly dependent on the environmental conditions the rubber has been exposed to versus time. A car that has low mileage, always garaged in reasonable temperatures, etc, will have a dramatically different aging process than one that has higher mileage and therefore many more heat cycles. Similarly, a high mileage car (or even a low mileage one) that has been outside most of its life will have a dramatically different rubber aging outcome (window surrounds, anything exposed to UV, even door seals due to large heat cycling ranges) for rubber components. It's not a simple "it is this old, so they are all the same" outcome -- an assumption like that could not be further from the actual outcome.

One example is the original front tires off my M5 I had in controlled temperature dark storage for more than 13 years I recently posted a thread on. They look as new. Zero dry rot/aging evidence at all. That said, they should never be used for serious driving of course since it's impossible to "know" the interior quality of the rubber-to-belt bonds with this age tire. However, a tire is a much different component with a totally different service profile than a door seal, window surround, rear main seal, CSB cover, etc.

Hence trying to guess the rubber aging on any given car is futile unless you have documented provenance of the car's storage and usage profile versus it's mileage which would include climate conditions.

All that said, on any used car a thorough inspection of many of the mentioned parts, and more, is required. Speaking of thrust arm bushings...those disintegrate LONG before they even had the thought of rubber aging! :)

The other point is that what needs "replacing" is actually a subjective measure for every owner...take the recent case of a long time board member who drove his M5 to close to 300k miles and then was stranded when the guibo exploded. He took pride in having that component last that long. Many here, myself included, inspect such parts and replace when they are not providing near new service conditions (i.e. any M5 with 50k miles likely needs a new one imo). He would argue you're spending money needlessly (and with a good reason to back that up). Hence the old adage that when you buy a used car, you're especially buying the previous owner applies very strongly. There are actually many owners who follow the belief that "if it's still rolling, everything's fine".
 

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Discussion Starter #6
This makes a lot of sense. Thanks!
 

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Im sitting at 63k on my m5 and not my daily, hell it aint my semi monthly or semi yearly but when I searched i was looking for the lowest mile example I could afford. Theres no right or wrong answer on mileage to me it was personal preference to look for one with least amount of exposure to "negative ownership" ie: just drivers of cars. I have shipswright disease so I expected Id be doing bunch work anyway once I got it and started baselining. I also lucked out and found out it was previously owned by board member who did a bunch of PM to the vehicle as well before trading it in.
 
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