Im new here and Im sure this topic has been covered but I can not seem to find any info on oils for AMG motors. I know the dealer recommends Mobil 1 0w40 oil, but when I first got the truck, with 60k miles, i did an oil change with the 0w40 and after a few days it seemed the truck started running louder and I even noticed some valvetrain noise, a few days later I switched to Mobil 1 10w40 high mileage (not a MB approved oil for this motor) and within 2 days the motor quieted down back to normal. I have since switched to Amsoil 5w40 euro formula and its been running well, but its pricey and I have to order it, so shipping ends up costing me even more. I usually go about 5k between oil changes. Should I stretch this out longer, goto a different oil, or stay with the amsoil (its not thaaat expensive but im always looking to tighten the budget when possible especially when the spending isnt justified)? I was considering trying the Mobil 1 0w40 again, thinking maybe it was a coincidence and I had a noisy or stuck lifter or something and it came loose, or it was just a fluke. Any thoughts on this situation?