What do I mix with a heavy clay soil to keep it loose

Perlite.

Hello! Here are a couple more options for you, Dennis. Click on the link below:

https://www.doityourself.com/stry/how-to-loosen-clay-soil-for-more-oxygen

you need to rototill the soil,add Peat moss. Gypsum,Pelletized lime,ultra light top soil.

We plowed a garden 50 x 50 ft and it was heavy clay soil too. We hauled a ton of sand or maybe 2 tons of sand and 5 or 6 bales of hay and worked that into the garden. Then we kept adding everything we could from leaves, grass, coffee grounds, ground egg shells, produce from peelings etc. Nothing was left out that could put bulk and fiber into that soil. It took a year or two, but we finally had a really great garden that produced many cabbages, raspberries, tomatoes, beans, squash, and pumpkins for us every year. In the fall we planted turnips and carrots and they grew in the ground. It was TN so the ground never froze.

Sand will help that clay in your soil. If you plan to grow flowers or veggies, then add manure too.

Amend your soil as your budget will allow.

Some ideas here

http://forums2.gardenweb.com/discussions/1590857/newbies-dealing-with-heavy-clay-soil

http://www.finegardening.com/article/improving-clay-soils