The 3.5 HO in my 300M is spec'd for 10w30, and it seems Chrysler is keeping that same spec for this engine in the new LX platform (Chrysler 300 and Dodge Magnum). Here is a photo of the engine I took today in a 300 Touring. The oil cap has "10w30" on it. The oil cap on my 300M doesn't specifiy a grade, it just has the API starburst symbol on it. There was also a 1961 300G on the floor for tonight's premier of the new 300. How's this for an engine?