I purchased my awesome 2007 civic 1.8l. It has 123,000 miles on it. The previous owner has been using 10w-30 weight oil. The owners manual suggests 10w- 20 weight oil. It's time for an oil change. My question is - should I go back to dealer recommendations and drop in oil weight to 20 weight oil ,or should I continue to use 30 weight??????? Thanks.