sorry to hear about your bike bro. but..
I have an OHC bike (pridor). When I drag the bike in racing etc activity, I change oil at 600KM (max). +when I travel on long routes I change is on 500KM. Viscosity of oil should also be considered as per the terrain and weather. In casual use, I use to change oil at 1000KM (Max). In winter i use AHL oil but in summer i use Havoline 20-50 or Shell AX7 Advance.
+ First oil I changed at was 300KM, then at 600km then at 1000 km then around 1970km. after 2000km break in period i took the bike for long journey with continuously driving between 80~100km/h for around 600KM and then back the other day again 600KM. All was ok.
So, moral of the story is that Oil change is a must on proper times as well as cleaning air filter, getting your bike tuned from best available mechanic on time as per manual. Cleaning drive chain and checking brake shoes pads, battery (and water level), head tail indicator lights, checking for loose nuts, proper air pressure in tyres, tyre condition and washing and wax your bike, checking race and clutch cables and oiling various components as per owner manual, setting air/fuel mixture and timing as per owner manual. These things looks messy in the beginning but spending time wd Pw bros and youtube instructional videos, one can learn quickly. And lots of helping bros here like Gul bhai(gs150), bro basic(gs150), bro vicky(gs/piaggio/cg), bro bluhorn, bro Amjad(AHL bikes), bro Naseer(CD100/Pridor) and many other bros who helps allot in learning phase. This way your new bike pays you back as a long lasting friend and as well as very good resale value.
I myself am interested to get a new GS (and an RP) but my affiliation with Pridor is not letting me sale it and i cannot maintain more than one bike.