If you're killing an engine in ~50k miles, sorry, but you're not properly caring for that engine. I've ridden for 45 years and I've never killed an engine despite riding, roughly, around the equator ~6 times. I've sold them at various, high (~60-90k) odometer readings with the engine still going strong. Have a buddy that just flipped a 100K miles on an 84 Honda 650 that he bought new in 84 and he got there on nothing but routine maintenance.
Rules:
1. Don't ride it like you stole it.
2. Buy the best oil and change it often (Mobile1 and Amsoil).
>For bikes where 1 oil lubes everything, change the oil every 2000 miles.
>For 3 hole bikes, Harley, change the engine every 2500 (use energy conserving Mobile1 car oil; 15w50), the primary every 2000 (Mobile1 Racing 4T 10W40), and the gear box every 4000 (Amsoil 20W50).
>Buy a reusable, stainless steel micron mesh oil filter from K&P or Pure Power (Both Made in the USA)...they are pricey, but they'll last the life of the bike and do a far better job than paper filters.
>Do not buy a cheap reusable, MADE IN CHINA, filter from places like ebay...they are JUNK and have been shown to pass more and larger particles than the cheapest paper filters.
3.Buy the service manual and do what it says when it says to do it.
No way you'll kill a bike in 50K miles following those 3 rules.
PS> The oil you're taking out is still, technically, "good" except for the abrasive particles floating in it...you can use it in some other engine. Head to ebay and buy a 1 micron filter sock, run the oil through that, then put it in an old car or lawn equipment.