You can continue to run the Ford Gold Coolant...BUT
you have to maintain it properly. (yes, I know that is a big but..no jokes please).
The problem with the Ford Gold is that the chemistry changes rapidly given the environment in which is is being run...so you must keep on top of the maintenance of the fluid.
The newest Ford TSB outlining exactly what that means came out 5/04/2009.
Copied/pasted below for your reading enjoyment:
DIESEL COOLANT MAINTENANCE - SERVICE TIPS
2003-2008 E-350, E-450, E-550, F-Super Duty
This TSB is to provide additional information to supplement the Workshop Manual (WSM) and Owner Guide information on the importance of cooling system maintenance for diesel engine equipped vehicles. Some customers, using their trucks under special operating conditions, indicate that operating with insufficient coolant strength (antifreeze or anticorrosion) can result in significant engine damage. Insufficient coolant strength can result when:
^ Cooling system pressure and coolant is lost.
^ The coolant level is topped off using the incorrect coolant.
^ The coolant is mixed with hard water.
^ Coolant is mixed at the incorrect concentration.
^ Vehicles are operated under the special operating conditions as defined in the maintenance schedule (heavy commercial use that results in frequent or extensive idling, frequent low speed/rush hour traffic use; vehicles operated under special conditions such as: sustained high speed driving at maximum GVWR load, towing a trailer, using a slide in camper (F-Super Duty) or car top carrier (E-Series).
Proper cooling system maintenance is critical for maximum engine performance and efficiency on today's high technology diesel engines. It is essential that; the proper coolant is used, the coolant level is checked routinely, the coolant strength (antifreeze and anticorrosion property) is tested frequently and that the cooling system is flushed (with Motorcraft® Engine Cooling System Iron Cleaner) at the proper intervals.
Check and maintain the coolant strength (antifreeze and anticorrosion) and flush the cooling system using the recommended service procedures and frequencies detailed below.
1. Inspect the coolant color as stated in the WSM, Section 303-03. If the coolant is not a clear or pale yellow color and has not had any coolant additive added, flush the cooling system with Motorcraft® Engine Cooling System Iron Cleaner and refill with a 50/50 mix of Motorcraft® Premium Gold Coolant and distilled water. No further action is required at this time. If the coolant is clear or pale yellow, proceed to Step 2.
2. Recommend measure coolant antifreeze strength. Measure the antifreeze strength following the recommended frequencies detailed in the chart below. A 50/50 mix provides protection to -34 °F (-36 °C), for operation below this level, refer to the applicable Owner Guide and WSM for specifications. Proceed to Step 3.
3. Recommend checking coolant anticorrosion strength. Check the anticorrosion strength (nitrite level) of the coolant using the Rotunda 3-Way HD Antifreeze Test Strip Kit part number 328-000011-800-Rotunda (768-8632) option 2 or equivalent. Perform coolant anticorrosion strength at the frequencies recommended. (Figure 1)
NOTE FAILURE TO FOLLOW THE SERVICE PROCEDURE AS INDICATED CAN RESULT IN INACCURATE TEST RESULTS.
4. Instructions for coolant testing:
a. Start with clean, dry hands and utensils.
NOTE DO NOT COLLECT FROM THE COOLANT RECOVERY OR OVERFLOW SYSTEM. COOLANT MUST BE BETWEEN 50 °F AND 130 °F (10 °C 54 °C) WHEN TESTED. ROOM TEMPERATURE IS PREFERRED.
b. Collect coolant sample from the radiator or pet****.
c. Remove one strip from the bottle. Do not touch the pads on the end of the strip. Discard strip if nitrite test pad has turned brown.
d. Dip strip in coolant sample for one second, remove, and shake strip briskly to remove excess liquid.
NOTE FOR BEST RESULTS FOLLOW TEST TIMES CAREFULLY. USE A STOPWATCH OR CLOCK WITH A SWEEP SECOND HAND.
e. Wait 45 seconds but no longer than 75 seconds after dipping strip to compare and record results in the following order:
(1) Compare FREEZEPOINT (end pad) to color chart on bottle and record result.
(2) Compare NITRITE (end pad closest to handle) test to color chart on bottle.
(3) The middle pad is for MOLYBDATE which is not a performance measurement used in determining maintenance requirements for these applications.
f. It is okay to estimate a value between color blocks, but if uncertain about the color match, pick the lower numbered block, for example if nitrite color is between F and E, use column E.
5. Coolant test results:
a. If the nitrite level exceeds 800 parts per million (PPM), no action is required, anticorrosion strength meets specification.
b. If the nitrite level is between 300 PPM and 800 PPM, anticorrosion strength is low. Add 32 fluid ounces of Motorcraft(R) Diesel Cooling System Additive.
c. If nitrite level is less than 300 PPM, anticorrosion strength is very low and cannot be restored refer to Step 6.
6. Flush the cooling system with Motorcraft(R) Engine Cooling System Iron Cleaner and refill with 50/50 mix of Motorcraft(R) Premium Gold Engine Coolant with Bittering Agent and distilled water as stated in the WSM, Section 303-03. A 50/50 mix of the Motorcraft(R) Premium Gold Engine Coolant with Bittering Agent and distilled water provides the proper cooling system protection and nitrite level for operating temperatures to -34 °F (-36 °C).
CAUTION DO NOT ADD MOTORCRAFT® DIESEL COOLING SYSTEM ADDITIVE WHEN REFILLING THE COOLING SYSTEM AFTER A COOLING SYSTEM FLUSH WITH MOTORCRAFT® ENGINE COOLING SYSTEM IRON CLEANER. THIS MAY LEAD TO POSSIBLE ENGINE DAMAGE DUE TO VERY HIGH NITRITE LEVEL CONCENTRATIONS.
7. Verify pressure relief cap integrity by using the WSM, Section 303-03.
8. Follow recommended coolant service intervals:
I couldn't copy/paste the tables associated with the above text....so I will post what was in those tables (as they pertain to the 6.0).
Under "normal operating conditions
Check the coolant strength
every 6 months. The initial coolant should be replaced at 105,000 miles.... subsequent changes should be every 45,000 miles.
You have the option (which should be mandatory) of checking the coolant NITRITE strength
every 15,000 miles.
Under "special operating conditions
Check the coolant strength
every 15,000 miles (24,000 Km) or 600 engine hours. Change coolant every 45,000 miles (72,000 Km) or 1800 engine hours.
Check coolant NITRITE strength
every 15,000 miles (24,000 Km) or 600 engine hours.
The next graphic I could not copy/paste is just the Ford part numbers/descriptions of the products they refer to.
: Motorcraft Diesel Cooling System Additive
: Motorcraft Engine Cooling System Iron Cleaner
: Motorcraft Premium Gold Engine Coolant with bittering agent
: Pressure Relief cap
: Rotunda 3-way HD Anti-freeze test strip kit
Now, given all the BS you have to go through to properly maintain the Ford Gold, you can easily see why everyone runs away from it (me included). That said, the Rotella ELC that the International Dealer sold you is a much better choice.
In your instance, if you have the proper gauges on your truck to monitor the deltas, I would actually leave well enough alone and go through the BS steps to maintain that Ford Gold as best as you can for as long as you can. Once your deltas indicate an issue with the oil cooler, that would be the time to tackle the full flushing procedure and swapping in the Rotella ELC.