I've only ever personally changed brake fluid once in any of the vehicles I've owned. oops! Had it done a couple of times most likely on a few brake jobs done at a shop, but I've also only had to replace one caliper ever, mostly due to torching bolts on that tired old wreck...

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1981 300SD - 283,000 KM's at purchase, 360k+ now. Engine replaced at 311k. 16" CLK wheels, w126 gen II cosmetic upgrades, late w126 leather interior. RIP. Parted and gone due to fire

1987 300SDL - 243K miles and counting. In winter hibernation!

2001 Ford F250 Super Duty "Platinum Edition" Lariat 4x4 7.3L turbo diesel, 295k+ miles, various mods for reliability and performance.