2002, 130k, green stuff running down the back of the engine. Prestone flush before and after gasket replace. Final flush before fill with green, take upper rad hose off radiator, attach a piece of 1-1/2 muffler tube to hose, hang over the front, garden hose in the rad, run for 1 hour at varied speeds, drain and top off with green. All is good.

 

in my 2003, i replaced LIM gaskets w/ the FEL PRO-upgraded ones IIRC at 85-95 k. it made a big improvement in the engine drivability---smoother starting, idling, more power, etc. i now use a Prestone dex cool substitute called 'universal or long life all engines'. pls don't use the old style DEX-cool long life. i like my good old reliable 4.3L V6 too much. Just do it before it becomes a major repair.

 

July 2017.

I bought the truck knowing the job needed done.

The cooling system was a mess from inadequate transitioning from Dexcool to traditional green as well as PO neglect. Finally got around to replacing the heater core and HVAC actuators while the dash was out. Flushed the system with citric acid crystals and installed an OE thermostat. I also pulled the engine block plugs to fully drain the system and get all the rusty grit and water out.. Refilled with Prestone Dexcool.