coolant is as important as any other fluids in a car. different types of coolant have different chemicals in it, wrong chemical characters could corrode orings and gaskets, resulting in premature engine failure
for example, cummins isc 350 engine specifically requires D6210 specifications, anything below than that will shorten the life of the engine.
it must NOT contain sodium 2-ethyl hexonate (this is an acid and will attack silicone seals and tubing).
toyota may not say something like this, better use manufacturer recommended coolants.