I recently had some major work on the engine (overheating) and I started hearing a ticking noise and the mechanic told me to put thicker oil to make that ticking sound would disappear. But it didn't, now the car has very low rpm on idle (about 600-700). I put 10W-30 and an STP additive so now I'm assuming is like a 10W-40. The oil dip stick shows that the oil is well above "operating range". I'm pretty sure that the oil is the problem but I would like to hear confirmation from you guys, I'm no car expert as you can see![]()