Science is what makes this a tough nut
GM's coolant is an OAT's formulation, Ford coolant is a HOAT's formulation and didn't look up what RAM's were during the switch from good old American Green.
Almost lost my 7.4L during that educational discovery period. While flushing with DexCool and still couldn't stop from over heating. Did discover that fan clutches comes in three levels of performance and will only use Severe Duty for my trucks
O = Organic
A = Acid
T = Technology
H = Hybrid
These 'new', compared to American Green, has a different process on how it works in any ICE.
Final result (as planned) has a protective coating over surfaces. Difference is some sort of organic material vs American Green's silicates (think of microscopic roofing tiles laid down over the surface)
Flush.
- American Green has no acid in it's formulation and required a separate or addition of an acid to etch the surface clean. Regular flush has a mild acid added during that flush. Harsh and very strong acid kits were for severe corrosion removal
Rinse the acid out and refill with American Green.
Complete protective coating (assuming the acid etch cleaned off the corrosion) took about 200 miles to complete that cycle
- OATs and HOATs has that acid built into it's formulation and is part of the way it works
OATs and HOATs takes several thousand miles to complete the protective coating cycle
There is are several 'buts' to OATs and HOATs...
That acid etches the surfaces and the organic then lays down a protective coating...but...there is no rinse cycle to remove that etched off corrosion. So there is metal oxide floating in there for 5 years. The assumption is that the remaining acid and organic floating around will re-etch and re-coat any spot that loses the original organic coating...
But...that now has a chemical brew floating around in all of the coolant. Okay if the closed system is kept closed (they why new systems no longer...not all, but most...no longer have a 'radiator cap'...to check either look through the over flow (it is NOT an over flow anymore, but pressurized holding tank) bottle material, or risk opening that bottle/radiator cap to check) and explanation below
Acid, organic and now etched off metal oxide floating in the coolant will have it heated to be more reactive to whatever comes along. If kept closed...not much going to happen as spec'd out...but...if O2 gets in there...like when you open it up to check or the biggie...a system containment break (AKA leak) develops...O2 will get into this highly reactive brew...
That will have the O2 react with the metal oxide and the organic. That then turns into a highly acidic & STICKY glob during a cooling down phase...like when the radiator does its job
But...that is in the radiator tubes, which is considerable smaller in cross sectional area.
So these acidic and sticky globs form...they stick to whatever. Mostly in the radiator tubes, but not just there. Some make it out of the radiator and into the rest of the cooling system.
Like the heater core and backwater areas in the ICE, etc...
This happens over time and will work (eat) its corrosive magic on whatever it is sticking to. If rubber...it will take much longer than if it stuck to metal...
That is why OATs and HOATs systems will warn to NOT mix them...especially with American Green. But to then flush every 2 years instead of the 5 years...
I've switched my 1996 Suburban's 7.4L to American Green after figuring that out. Someone posted a link to my radiator shop's web site. DeathCool is what we all DexCool... Previous radiator shop guy went to high school with retired after about 6 years of DeathCool appearance. He had about 6 times uptick in business from the day his father gave him that business...mainly from local dealers who gave up trying...
Flashman wrote:
Is this just a Ford thing or other diesels as picky?