A little advice from an old guy... DON'T USE CINDER BLOCKS! They're not safe.
Concrete masonry comprises two basic types - cinder block and concrete block. Concrete blocks are pure concrete, whereas cinder blocks are made from coal cinders and concrete - forming a lighter, cheaper, building material.
A long, long time ago all quality building blocks were made of concrete... thus concrete blocks. These blocks were extremely strong and you could safely support a considerable heavy vehicle on them while working under it. A good concrete block will not crumble, a cinder block will, thus resulting in you not living to enjoy your retirement! DON"T DO IT!
