It used to be said that you could mix weights but should not mix brands. I wouldn't be too concerned with a one-or-two time change in brands anymore, so long as it's not a habit. I run Valvoline 10w-40 in everything with the exception of my AMX which runs Micron-Moly 10w-40. The Eagle was run on Pennzoil (bleckkk) prior to when I got it, I switched and now it too uses Valvoline. Now is a good time to switch to the brand you prefer and then stay with it.