I have not changed or added coolant to my 2006 f53 as I bought it used. I am not familiar with the yellow gold coolant and have never used it in other vehicles. My 2006 chassis manual says:
• Add Motorcraft Premium Gold Engine Coolant (yellow-colored), VC-7–A (U.S., except CA, OR and NM),
VC-7–B (CA, OR and NM), meeting Ford Specification WSS-M97B51–A1.
Note: Use of Motorcraft Cooling System Stop Leak Pellets, VC-6, may darken the color of Motorcraft Premium Gold Engine Coolant from yellow to golden tan.
• Do not add/mix an orange-colored, extended life coolant such as Motorcraft Specialty Orange Engine Coolant, VC-2 and VC-3 (US) or CXC-209 (Canada), meeting Ford specification WSS-M97B44–D with the factory-filled coolant. Mixing Motorcraft Specialty Orange Engine Coolant or any orange-colored extended life product with your factory filled coolant can result in degraded corrosion protection.
Perhaps one of you could help me understand if someone has mixed the yellow and green. If so, I should replace. I can see green on the top of the gold.