I put $30 worth of 5w30 M1 Syn High Mileage in, less than a week later I lost all the fluid in my cooling system on the road from a bad hose. Engine got up to about 260*F. Can the oil handle these temps, or is it in need of changing again. I can't smell a difference on the dipstick, but then again my whole engine bay smells like coolant. Is the oil ok to withstand those temps or have the chemical properties been modified and I should change it again?