On last oil service I specified 15-40 WT. At about 2K miles idle went to .3 bar and would not reach 3 bar when hot. Oil seemed very thin and I had changed to 15-40. I watched them open thecans this time. Now pressure when hot is 1.3 bar at idle in gear and 3 bar at 1300 RPM. I have had car some time and this was scare. Never any lifter or chain noise on startup. Same independant shop underfilled my 300E by 2 quarts. Also very thin oil. Had been pleased with shop until now. They must have used their Volvo mechanic.