::sigh:: Old cars had instructions on adjusting valves because you needed to. Improvements in manufacturing processes means that valves and valve seats simply don't wear the way that they use to. You may still need to change valve shims if your clearance is out of tolerance, but on most cars that's going to be well over 100,000 miles before service is needed. It's also a really tedious, long job, and takes tools that most people aren't going to have. (I have done it multiple times on a motorcycle; that's a 10,000 miles service interval b/c the engines on the bikes I ride redlines at 18,000rpm, which means significantly more wear on engines, and higher chances of thing like valve flutter.) Cars are vastly more complicated than they used to be, because they're also far, far more efficient, and last far longer; it used to be a big deal if a car made it to 100,000 miles, and now a car that dies at 100k is considered an unreliable lemon.

[–] horse_battery_staple@lemmy.world 4 points 1 day ago* (last edited 1 day ago) (1 children)

Well, they don't last far longer as a whole, but the advances in machining tolerances and material science, the mechanical internals can go far longer without anything more than fluid changes.

As far as longevity, soy based wiring harnesses, poorly shielded ECUs, and borked software updates are what are killing cars these days.

[–] HelixDab2@lemm.ee 0 points 1 day ago

As a whole, they def. do last longer. I can look on FB Marketplace right now and find cars that are in fairly good, operational condition with 250,000 miles. The issues you're talking about aren't the kind of major mechanical things that become improbably expensive to repair, e.g., a broken timing chain with high interference valves & cylinders. Although yeah, replacing a main wiring harness on a car is a PITA and very expensive unless you can find a functional used one on eBay.

Also, there's not great empirical evidence that the soy-based insulation is significantly worse than its petroleum based counterpart. There's a ton of anecdotal claims about it attracting rodents, but no direct evidence AFAIK. The class-action lawsuits over rodent damage have been dismissed. And, TBF, I've had older cars that had wiring chewed by mice. Part of the difference with newer cars seems to be that there's just more wiring packed into smaller areas, areas that look like great nests for rodents; you didn't see that kind of wiring density 20 years ago.