OK I'm new here so pardon my spelling. My question is, what is the difference between 5W20 and 5W50 engine oil. From what I have been told the 5W stands for winter flow or cold starting flow rate ( viscousity )and the last number 20 or 50 is the rating for high temperature protection of a single grade oil. The oil does not thickin to 20 or 50 it just protects to that weight. Hondas recomend a 5W20 and I question why a 5W30 or 5W40 can't be used in that or any engine being that the 5W oil is used. I have used 5W50 with no problems in my last car for 100,000 miles and never gave it much thought. I think that it cost more to produce oil of 5W that protects up to 40 or 50. European blends of oils are also comimg into our markets and wonder why we are behind or are they any different then ours? My MB C Coupe only recomends certain oils that pass 229.3 testing. What makes their engines different from other cars? Thanks for the help here!!