specifications. If your vehicle was originally charged with R12 refrigerant, for example, the oil type specified, 'mineral', will not apply. Additionally, General Motors issues Bulletin # 02-01-39-004B replacing PAG 150 oil with a lower viscocity oil.
The term square in reference to roofing materials refers to 100 square feet of roof area. One square of slate is the amount of slate that it takes to cover 100 square feet of roof area. A 10 foot x 10 foot section of roof would equal one square. So would a 4 foot x 25 foot section. Ditto for a 5 foot x 20 foot.
If your roof has a section similar in shape, double check your sketch to make sure that every piece is either rectangular or triangular. s = (15'  15')/2 = 112.5 square feet. t = 40'  15' = 600 square feet. Remember to check both small triangles in the center part to make sure that they are the same size.