On my Apache O-320 engines I used to have the oil go dark within 20 hours after an oil change, It was not blowing oil out but was consuming it about a qt to 2-3 hours (depends on power setting)
The engines are high time 5000 and 6000 hours total and had 900 and 1600 hours respectively since the bottom ends had been overhauled. And we found a cracked cylinder one day chasing a low leak down test, so the time had come. (They were overhauled cylinders that had been put on at various times. The previous owner was "very" frugal)
I tried to get new Lyc cylinders but couldn't. ECI had them. Discussed with my engine guy and he is comfortable with taking the bottom ends out to near 4000 hours SMOH.
So, we put 8 new Titans on with ECI moly rings and Lycoming wrist pins.
While the cylinders were off we did as good an inspection of the bottom end as we could - borescope, mirrors, etc. Everything was clean and tight, the con rods had no slop and the cam looked great. I also sent the oil coolers out for testing and installed new Vernatherms, some new hoses, etc.
Have a few hundred hours on the new cyllinders now. Biggest problem is the oil stays clean and bright and I have to remember to check the logbook or I go over my 50 hours. Before it always got dirty enough at about 35-40 hours that I was changing oil because it looked and smelled grungy.
So, pull a cylinder and check the cam and inspect the bottom end. If it looks good don't be afraid to put on new cylinders.