The brand is irrelevant really as long as you stick with the correct viscosity and really boils down to personal preference. The 2010 RX requires 10W30 or 10W40 oil. I personally use AMSoil Series 3000 5W30 in my current (and previous) RX as it has a high TBN and HTHS. Oil analysis on my previous engine showed no wear. As long as you use the correct viscosity, Mobil 1 should be fine.