Some time back guys here told me to start using 15W40 in our 270,000 VX Accliam for the lifter noise and overall performance. Just reading another post about lifter noise and the guys say use 5W30 and 10W30. We live where its 35 to 40 during the the 6 summer months and a lovely 15 to 20 during the 6 winter months, I now read this has a lot to do with which grade of oil to use. We tow a camper trailer a lot and change the oil every 10,000 and because of the lifter noise we also use a lifter and a worn engine treatment which reduces the ticking completely for 10,000 ks. Are there any professionals here that could recommend an oil to use or is it just by trying different oil grades the best way to see which oil is most suitable to an engine. I know this subject is never ending but I am concerned that we might be using the wrong oil or does it really matter which oil we use.