My friend had one of those T's on her car and after a couple of years it cracked and leaked. You could probebly do as good a job by just opening the 2 drains and taking off the thermostat. I don't know how easy that is in your car. Mine was pretty easy. I wouldn't want that Prestone thing on my car. A radiator guy told me not to use those cleaners also.

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra