I have an oil slick within my t-zone area after four hours (I timed it) if I don't do the following:
* I remove my make-up the night before, so when I wake up, I use Neutrogena Clear Pore Oil-Eliminating Astringent to remove trace residue of foundation. I do this before I wash my face because if I do it after, there is some slight residue of the product left, which I don't like.
* Then, I put Queen Helene, Mint Julep Masque on my face and let it dry. This is an old school product, but it certainly works for me. But I only do this every two days to keep my skin from over drying. I ONLY put this product in my t-zone area, where the oily area is.
* Afterwards, I wash my face with Neutrogena Rapid Clear Oil-Control Foaming Cleanser. This stuff is great!
* I then apply Ahava Matifying Moisturizer. It's pricey, but it's worth it to me.
* Lastly, before I apply my make-up, I apply MAC Multi-Purpose Matte. It's like a primer.
I also carry around blot papers and MAC Blot Powder. This is not to say that this regimen will work for you, but perhaps this will give you an idea and tips to try. It's a lot of work to do in the mornings, but it's worth it to me.