87 Audi 5000 overheating

After detecting white colored sludge in the overflow reservoir, I cleaned and flushed the radiator coolant.
Now, in stop-go traffic, the car still overheats occasionally.
I am speculating that the radiator core is still congested with the white sludge, which mostly likely formed due to using the wrong antifreeze coolant!!!
The car also failed the California Gross Polluter smog test. (The NO (PPM) figures where slightly out of range to the upside.)
I have read this could be caused by a too high burn temperature in the combustion chamber. The sparkplugs tend to confirm this by displaying a white color, and likely caused by the overheating.
I think I will remove the radiator and do a reverse flush with a garden hose. Most likely this will not work and there may be no other way to flush the radiator with chemicals.
This experience confirms that the audi must have the right antifreeze solution to minimize this kind of mess.
Anybody out there with a similar experience?
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Try to run a compression test. Sludge in the coolant may be an indicator of a blown head gasket and oil getting into the coolant. The light color on the plugs might be due to coolant getting into the cylinders. If this is the case it is a very doable fix.
It could have been blown as a symptom of your cooling problem.
Is your radiator cooling fan operating in all three speeds and at the right temperatures?
Tstat stuck closed?
martino wrote:

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wrote:

Thanks for the input!
I see some good point and will put my working clothes on in the coming week.
I wouldn't be surprised to find multiple problems. However, must say the car is running fine, performance wise.
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