International ProStar: Used-Buy Risk, Repairs & What to Check

From the research record

• PRICE: - TODO: unsourced (fetch blocked). truckpaper.com International ProStar day-cab and sleeper listing pages returned year/mileage/spec data for 28 listings each but no dollar price in the extracted text after 2 attempts per page. commercialtrucktrader.com returned a CAPTCHA/"human verification" challenge through the proxy on every attempt.
• FAILURES: - An owner weighing a full ISX rebuild describes the motor as not yet showing major issues, but flags "right around 800,000 miles" as when this class of rebuild decision becomes live: "we're not having any major issues with the motor... yet, a lot of guys are telling me [wait]" (video transcript: https://www.youtube.com/watch?v=kP3vMQJaAFI @ 00:00:
• REPAIR: - Full rebuild quote: the owner's stated threshold to commit is "somewhere in the mid 20s to low 20s" — i.e., roughly $20,000-$25,000 (video transcript: https://www.youtube.com/watch?v=kP3vMQJaAFI @ 00:02:23-00:02:33). - The "classic" rebuild tier being quoted covers the water pump and "everything but the turbo" (video transcript: same @ 00:00:43-0
• LIFE: - Documented service life of 500,000+ miles achievable; fuel economy 7-10 MPG typical; base warranty 2yr/250,000mi, extended 5yr/500,000mi. https://www.cylinder-heads.com/cummins-isx/ - Owner testimony above suggests some operators push well past 500
• VIDEO (00:00:58 https://www.youtube.com/watch?v=CrDuDh0DsbM): "thing. And luckily for me, it's a relief valve cuz injectors are about $1,000 a"
• VIDEO (00:01:00 https://www.youtube.com/watch?v=CrDuDh0DsbM): "valve cuz injectors are about $1,000 a"
• VIDEO (00:01:00 https://www.youtube.com/watch?v=CrDuDh0DsbM): "valve cuz injectors are about $1,000 a piece. So, we're starting it. And uh"
• MARKET (soarr.com dealer inventory, 15 listings observed 2026-09-05): low $16,950 / median $25,000 / high $70,904. Claude-refetched: 15 used International ProStar listings (2010-2018, 162k-576k mi), $16,950-$70,904, median $25,000.