What is the acceptable oil pressure range for my engine. When cold it's at 3.5 bar. At operating temp(at idle) it's as low as .5 bar. Is this normal? I got the S4 with 100,500 miles back in 2008. The previous owner changed the oil(conventional 10w-30) every 6000 miles. I've driven it 15k miles over the past 5 years and kept the same oil change schedule. Could the oil pump be going bad or is it possible that I've got leaking injectors?
Should be at 5 bar at start up and when driving. 2 bar or a little lower at idle. I change the weight of your oil before doing anything else. Also make sure the gauge is working correctly. Are you using the correct Mann or Mahle geman oil filter?