I mixed "universal coolant" with Toyota coolant. Am I screwed? Do I need to get a flush ASAP? There is soo much debate on this topic I can't be sure what the correct answer is. Of course the dealer is telling me I need a flush soon...
Just flush it when you can.
It won't die but can get gluggy and flow slower some of the smaller holes over time.
I'd do it sooner rather than later but its not like its suddenly going to gum up.
Just drain it and fill the system with some tap water, run for a few minutes, don't forget to open the heater vent. Drain, refill with water and run to operating temp to make sure the thermostat opens, drain again, then refill with toyota red and jobs a good un.
Take out the thermostat and run a garden hose through it and flush everything out till it runs clear put the thermostat in drain the radiator put distilled in, run it drain it fill it distilled run it drain and refill with 50/50 Toyota red and distilled and you will be fine