Bought a 1990 LS 400 in October. 1 owner car with service records -123K miles. I've been doing some preventative maintenance as well as upper control arms, plugs/wires/ACV, PCV, etc. I was going to move onto brake rotors but I noticed that the engine coolant is prestone green. Should I flush out the coolant and refill with Toyota pink or leave it. Can't find a service receipt for radiator flush so I don't know how long its been in there.