Grays and Whites

I'm having a problem with my whites. I don't have a consistent white formula that I use while painting, instead I mix a new batch every time I sit down, and most of the time I use a very haphazard method of using a little of this, a mess of that, whatever looks good, etc. I'm looking for a color that is off-white, but not too yellow or blue. It's really hard to find that perfect color.

So I've been experimenting a bit with the whites and grays that I use when I paint in oils. The above are two of my favorite whites. I think I have mentioned Archival Fast-Drying White before, I really like it and use it for almost all of my mixing. For a gray horse, though, I'm trying out Archival's Tinting White. I bought this a while ago and didn't use it because I thought it would take too long to dry. But guess what? It's not too bad! It's slightly off-white, with a pearly sheen, and the consistency is really soft and buttery, which I like. Here's a little comparison of them, with a buff titanium I've been using to show how different that color can be:

I've been adding just a touch of the Buff Titan to the Tinting White, and then a smidgen of a gray mix to use for my grays. 

Now on to the grays. I also have a problem with my grays getting a little too blue for my taste. I used to use Burnt Umber and Mars Black, with a touch of a yellow ochre, but lately I've been mixing equal parts of Raw Umber and Van Dyke Brown plus a touch of Mars Black. Today I made this little chart of different mixes to see what worked best. I was surprised to see that I liked the mix with the two browns and Ivory Black. I usually equate Ivory Black with blue, but it looks pretty good to me. Mars Black is a stronger tinting color than Ivory Black, so maybe that's why.

You can click on the grays for a larger photo.

So, what do you think? Do you have a favorite "recipe"? I would love to hear what other artists use for their whites and grays when they paint in oils.