oil in fe question.
 

right now i use the cheapest oil i can buy conventional 10-30 from supertech *wallmart brand*

i bought some royal purple for my wife's minivan *not as a performance boost or any thing just wanted "better" for that junker* and then before i got my incredably unhappy about it lazy self out there to change the oil *i hated that van* it had a whole mess of problems break loose and we got rid of it. *put more work into that lemon than any vehicle i ever seen it was baad so much work pepboys was giving 30-40% discount of labor and free alingments*

any way now i have her new truck my truck and like 5 qts of 10-30 royal purple. i been told directly by the dealer ship that the royal purple isn't needed or that much better for the new truck sooo....

would the royal purple be of any benifit to my 390? it is in a 71 250 that isn't in the greatest shape but it runs.

i ask because i have heard that if you switch from conventional to synthetic you need to on your first oil change after the conventional has been replaced with synthetic change your oil again at like 1500 miles instead of the 3000 so that it flushes out the conventional. then you are good to go at regular or recomended intervals. and the same in reverse when going from syn to conventional.. so if there really isn't any real advantage all things considered i would rather just stick with the supertech unless synthetic does some thing better not expecting any real miricles but better lubrication or cooler temps or longer intervals would be worth it if they are safe for the engine.

Anyone with an opinion? ;)