You do not require coolant and we did not use coolant in our 7x12. I only changed 3 blade's in 18 months also almost daily cutting, some days it would cut all day, but the bigger/ tougher the material the more heat .. Friction -heat - expansion - fatigue. When cutting large stuff I would use a bit of rapid tap to aid, however when using coolant the cuts are cleaner,blades do last longer and noise is also sequestered slightly. I used white coolant back in high school and green in the shop both work and in theory you could use straight water the only draw back would be the rust.
Cutting a quick bit of mild steel? no need to lubricate/cool, cutting 4140 log? Coolant!