Oil quality is very important in the 7.3 power stroke engine. The high pressure oil system on these engines is very sensitive to to air bubbles. When the oil breaks down as it gets older it will lose its viscosity. When this happens the oil will start to hold air in it. When there is air in the system it will not hold the pressure as well. If your truck is running rough and you have not changed the oil in a while it may be a good idea to do that first and save yourself a repair bill. Also if you have just changed the oil and it has started running rough make sure the correct oil is in the engine if you are unsure I would go ahead and change it again. People have misdiagnosed trucks a lot when it just had old or the wrong oil in it. Save yourself money on repairs by just trying that first. For any questions or if you need your truck looked at give me a call (678) 920-1187.