RPM's while on the interstate/turnpike...

[nobrakes]

I have had my 02 S for just about a year now and have totally enjoyed it. Love the look, ride, sound, feel and smell.............I have learned a great deal from this forum and greatly appreciate the knowledge here. I know that to keep the oil circulating well its a good idea to keep the RPMs over 3k, but what about driving on interstates, expressways and turnpikes where speeds are over 70mph for extended periods of time and 6th gear (S) is used?.......Is it alright to keep the RPMs between 2700-3000 for better mileage,quiet ride and efficiency? At what speed do you use 6th?........Thanks in advance.