I'd stick with the proper oil grade Lexus calls for your RX.......& stay away from Fram filters.....they are crap! Either stick with Lexus (or Toyota), Mobil 1 oil filters , which us Canadians are only able to get in the States.....or a K & N oil filters available at Canadian Tire (I usually wait till they are on sale in their flyer & buy several). Did you get service (oil changes history on the RX mess?
I think your RX has the pink 'super long life coolant' which is good for 5 years & over 200,000 kms? so I wouldn't add the royal purple stuff as the factory coolant is heavy duty stuff as it is. ;) I'd also consider purchasing a 'Lexus' extended warranty.....if something goes worng after the warranty expires, it's worth it's weight in gold! Good Luck! & welcome to the club. B)