i usually apply moisturiser and sunscreen 30sec after that, so it's pretty much mixing them together. but i was wondering about actually mixing them before application.

I actually wondered about this same question for myself. As you can tell from some of my other comments, I may be a little too casual about sun protection, so you have to take my comments with a grain of salt. But my thought is in part it depends on how fair you are, how long you'll be out, and how much risk you feel comfortable taking in terms of the sun protection. I agree it would probably dilute the sunscreen, but if it were me, and I was in a rush and just looking to add SOME sun protection to my daily moisturizer for brief, daily sun exposure, I'd probably chance it for the convenience (knowing that I might not be getting the same level of protection as if I put on sunscreen on top of moisturizer). But if you want to be absolutely sure you are getting the full SPF, I'd do the sunscreen separately. As an example, I use a product with SPF 10 for everyday (i.e., drive to work). It's not much in terms of SPF but it's a convenient product that doesn't break me out, so I know I'll be willing to use it every day and, to me, that's better than higher protection that I won't want to use if I'm in a rush. With the ol' rosacea, my morning routine has been complicated because I put the rosacea cream on too, so I try to keep things simple...