I have a 2003 Honda CRV, and they recommend you use hard-to-find 5W20 oil, supposedly for increased fuel economy. I did some web searching on this oil and there seems to be a couple of schools of thought on this. One is that the increased MPG is negligible, but the engine won't last as long with 5W20 so it's better to switch to 5W30. The people that say this usually recommend a synthetic 5W30 (esp. Mobil1 or Amsoil). The other side says it's better to use some xW20 oil as the dealer recommends, particularly Mobil1 0W20. (I don't think they make a 5W20.) I think the rationale is that the thinner oil is needed to lubricate the smaller gaps in thsse engines, or something like that. So I was wondering what people here that have cars for which 5W20 is recommended use, and/or what do the oil experts out there recommend? Also, would 6K miles be too soon to switch to a synthetic oil?