I went to do a basic maintenance on my 1990 300zx Twin Turbo. An engine swap was done about a year and a half ago, the previous owner never gave it an oil change, new coolant and kept the 1 and a half year old gas in it. So when I drained my coolant it was orange and a rusty color. I drained it out using water and I cleaned the coolant reservoir then put new coolant in it. Weird thing is I drove this car about 2 hours from where I got it and it never overheated with that rusty looking coolant, is that normal?