...on a mk1 996 I'm having a really loud valve noise of the left cylinder bench.
After doing an oilchange to the original oil and a cleaning of the engine with some special liquids, the noise has not gone. I was also driving for 20 minutes in the 3rd gear on the highway with a high oilpressure for letting the oil circulate. All these tricks did not help.

Is it dangerous to drive around like this? Does anyone have experience with and has some advice???