Can I use Clairol complements color intensifier with other permanent hair color brands?

I just bought Clairol complements color intensifier in Red and Purple. I also bought L'oreal Preference permanent color in MR8 (medium intense deep auburn). I was told at Sally's Beauty Supply that it would be ok to use the color intensifier with the Loreal color that I bought. Is this correct? Does the intensifier only work with the other complements line? I want a violet red and wanted to mix a little of both in with the main color. If it will work, does anyone have a recommendation on how much to put of each color, or will I just need to try some mixes on a stand test? Can I even mix the red and purple together? One more thing, I have a lighter Medium brown hair, is a 20 vol developer high enough? It was last colored red in July. I have colored my hair before but it is never very intense would a 30 vol make it more noticeable? Thanks for any help. And sorry so many questions at once.

Can I use Clairol complements color intensifier with other permanent hair color brands?
While the manufacturer will say no to your question, some brands can mix okay together. Your idea of the strand test is the way to go. What is your goal with your hair? More red or more violet? That will tell you which color you should add more of. When adding the "purple" use only a few drops at a time. Going to a higher volume will NOT help this be more intense for very long. It will fade VERY quickly. If you are wanting a more artificial and shocking color then I would not use this type of color. You should prelighten and then use a brand such as Cellophanes or Manic Panic. So to go over what you need to do again: Decide level and intensity of color. Do several strand tests to see outcome. Possibly prelighten for more intense color. If you went to a salon that works with Wella Kolestan they have beautiful double pigmented reds, red-violets, violets and violet reds that are very long lasting. Best of luck.