@Wallygator is correct, the oil change interval is every 600 miles. A lot of guys are changing the oil within the first 200-300 miles, but after seeing how clean their oil was I elected to stay with the factory recommended schedule and I will be changing it for the first time at 600 miles which is rapidly approaching. I have attached a snap shot of the maintenance page from the owners manual and aside from checking torque specs and spokes, radiator, valves etc. I plan to stretch my oil changes to every 1,000 miles after the second scheduled oil change at 1,200 miles, if everything looks good.
In regards to this bike being a good "overland" option, I think everyone's idea of what makes a good overland travel bike differs. In my eyes a good overland travel bike would constitute a bike that has a large tank, requires very little/low maintenance, and can handle the extra weight of gear on the sub-frame/pillion. The CRF450L embodies none of those, it needs a larger tank (only 2.01 gallons from the factory), see service intervals above, and the factory recommended specs for subframe load capacity is around 235 lbs, that said lots of owners have been surpassing that on the regular with no issues. Can it be turned into a bike that would excel in that category, for sure, but IMHO there are better options out there. Out of the box this is a big enduro with a plate, it is not a light weight dual sport or adventure bike as they would have you believe. This bike is a direct competitor to the KTM 450 and 500 EXC or the Husky FE 501, a large thumper for the woods that is street legal from the factory. While it is hands down the very best on-road bike in that category, it is still buzzy and light at highway speeds in comparison to the mid-size adventure bikes. In other words, it is not a bike I want to be riding at 70-75 mph for hours on in while covering tarmac miles.
The KTM 690 and the soon to be released 790, the Husky 701, Triumph 800, BMW 800/850, KLR 650, and hopefully the soon to come Yamaha Tennere 700 are all what I would suggest for someone looking to "overland" on two wheels. Light adventure aka Dual Sport bikes reign king in this category and are more adept at covering long days/hours/miles in the saddle but are still capable of traversing rather questionable off-road terrain.
My plans for this bike include a larger fuel tank, either the IMS 4 gallon or the large Safari Tank (both coming out in the fall), some small no-frame saddle bags, and possibly a tail rack. I intend to travel with it and take it on trips like Baja this fall, Colorado/Nevada/Utah BDR's, Big Bend, Palo Duro Canyon, etc. Trips that require covering 100-200 miles mostly off-road in a day but might have some tarmac time thrown in. Ride to the trail head, rip all day, then ride back home kind of bike. Eventually I'll add a 300 two-stroke for hard enduro type trail riding and maybe/possibly/not sure a mid-size adventure bike should I ever get the itch to cover more road miles in the future, but that's a long shot. I prefer to dodge trees and small animals on the trail these days instead of dumba$$ drivers texting and not paying any attention to riders on the street.