I follow the 600 mile oil change intervals and 1,800 valve inspection checks - no adjustments required so far. If you are an offroad Hero and mechanically inclined - get the KTM500. If you enjoy riding some technical offroad and want to focus on true dualsport and accumulate more miles over many years, get the CRF450L.
If you want something that will last (and has all the little bugs worked out), look at the Kawasaki KLR 650. Pretty much indestructible. If it's not aggressive enough for you, consider the Honda XR650L - also reliable as a pile of bricks. If that's not elite enough, a BMW F700GS (or 650) should do the trick.

700 hours at 25-hour intervals is 28 oil changes, or 56 qts. 90 - 56 = 34 quarts = 8.5 gallons of oil. call it $20/gallon (Rotella T6, $21-ish if you catch it on sale at walmart, usually $25-28/gal), that's $170 worth of oil that you really didn't need to change.

There are quite few other factors at play here as well when it comes to maintenance intervals. Cam design and how it interacts with the valve train will greatly alter valve service intervals as will material usage and density. The list goes on and on as to why the WR250r has a lower maintenance schedule. Oil Change interval? The manual says Motorex 10w50. Royal Purple 10w40 came highly recommended. Oil Filter Interval? Any better aftermarket filters for a lower price? Long and Short Screen cleaning interval? I had originally planned to clean every oil change. Valve Adjustments? How often should I be checking? TEMPS D'ENTRETIEN KTM 4 450/500 EXC-F Année-modèle 1 h 15 h 30 h 45 h 2017 65 90 161 90 àpartirde 2018 65 90 161 192 500 EXC‑F US Année modèle 50 km 750 km 1 500 km 2 250 km àpartirde 2020 66 90 161 192 250/350/450 SX-F Année-modèle 1 h 10 h 20 h 30 h 2011-2015 90* 180 220* 250 250/350 SX-F Année-modèle 1 h 10 h 20 h 30 h 2016-2017 . 114 396 210 301 386 387 325 300 395

ktm 450 exc oil change interval