Noisy lifters cause cam wear. Every time you hear your lifters ticking, its knocking a bit of metal off the tip of the cam lobe. Inspect your cam lobes closely and you might notice a wood grain pattern on the tip and ever so slight sharpening of the the tip. I've seen this on several OM603s including my own with noisy lifters. It took me a while to find an OM603 cam in the JY that didn't have at least one or two worn cam lobes. If you have noisy lifters don't ignore the problem because it goes away after the engine warms up. Replace the lifters NOW to prevent anymore wear on the cam. The new INA lifters are externally different.
The old factory lifter left, new INA right. The verticaly channel helps maintain oil pressure in the lifter even when its pressed down by the cam.
You can also place a couple of small neodymium magnets on the metal top of your oil filter cartrige. This will trap any floating iron particles in your oil. You'll be amazed and disgusted at the black tar like substance you'll clean off the margnets after an oil change. A magnetic oil drain plugs also works well for this.
Not too long ago another forum member posted the PDF I attached below. You might find it helpful.