Hey everyone! In my 2017 Miata owners manual it says "Replace at first 192,000 km (120,000 miles) or 10 years; after that, every 96,000 km (60,000 miles) or 5 years." for the engine coolant. My question is what is so special about the first 120,000 miles/10 years or what is so special about after the 120,000 miles/10 year? In other words why not just do it every 60,000 miles/5 years or the 120,000 miles/10 years?
Once cars get over 100k you start to get a lot more contaminants and efficiency drops. Contamu comes from outside sources or from the metals and plastics in the components. You also start to develop corrosion, calcium and other crude. This happens when coolant evaporates and coolant interaction with metals and plasticse over time.. Cars tend to run hotter as they age that will also decrease the coolants life span.. Same rules apply for oil , transmission, diff, power steering, breaks ect . Age, contamination and a system that just isn't as effective all lead to fluids being done sooner.
