I change fluid on running cars every three years; If the fluid was fresh, I can't see why it would degrade if it were garage kept, and low mileage.
I would use the flush, which includes driving it a bit to circulate the flush, then drain it well.
There's a plug on the side of the block that helps, if you want to be thorough in draining it.
Search for photos.
After I drain it carefully, I remove the thermostat housing, upper and lower hoses, hook a hose to the system, and backflush everything for a while. Move the hose around
I loosen the heater core from the valley line, and flush thru there as well. The lines at the manifold and the HCore are fragile, I don't dink with those.
I fill the antifreeze first, then add water; corrosion inhibitor is in the AF, lol.
A lot of businesses have Thermal IR cameras these days; Use one and look at the radiator and see if it's blocked off; it should be fairly even all the way across, top to bottom.
Otherwise is bad areas, They're easy as hell to see.
Red '96 Cougar XR-7 240k mi. '02 4R70W, PST DS : '03 PI engine, 04 maf, 24lb injectors, 2.5" exhaust, '02 4r70w + Jmod, DirtyD0g TC + cooler + 3/8" lines, 255 walbro fp. Alpine system.
Black '96 Cougar XR-7 (Lazarus) 210k mi PI Intake, '02 4R70W, Jmod, PST DS, GrogTune, Konis, Mark LCA+Poly, racecougar Custom Engine Chain, and JL and racecougar Bracing.
Black '97 Tbird Limited Edition, '02 4R70W, 255 walbro, PST DS, PBR Brakes&SS lines, Toicko Blues & Springs, GrogTune.
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