Rattle ticking noise just started

[Stevo96]

Hi, car is 03 4.4i m62.
I've had a few oil leaks since owning the car but the car has always started smooth with no rattles, I decided to put a much thicker oil in a few weeks ago and all was ok, no rattles or anything like that but the oil leak remained. I decided to put rislone main seal stop leak in to stop the oil leaks. Oil leaks have slowed considerable and car had no rattles. 2 weeks later the car started to make a rattle noise at start up for a few seconds then go away, engine sounds fine for 2 mins after start up then a noise appears like a loud ticking that speeds up as the revs rise but disappears after 3000 revs, it sounds terrible whilst idling especially when the engine is warm. Any ideas? I'm not sure if it's got anything to do with those additives I put in but thought it best to mention it..
Today I dropped the oil, did an engine flush and filled it with the correct oil, rattle remains.. Engine feels lump at idle which coincided with the rattle/ticking..