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Unless you know the maintenance history of the truck, it would be a good idea to do a complete flush. Coolant isn't that expensive, and by flushing you'll know where you stand.
As an alternative you could drain a portion of your coolant and then top off with fresh 50/50 (with no SCA added). This will lower your SCA level by diluting the old coolant/SCA solution with new coolant.
If your 3-way Fleetguard test strip is showing a reading of Molybdate (scale on left side of chart), then the coolant was not replaced with the Gold, or it was not flushed completely when changed out. The Gold is a Nitrite-only coolant, meaning that zero Molybdate is present. And the Gold will not have 3.1 Units of SCA even when new (at best it will have minimum SCA protection).
Unless you know the maintenance history of the truck, it would be a good idea to do a complete flush. Coolant isn't that expensive, and by flushing you'll know where you stand.
As an alternative you could drain a portion of your coolant and then top off with fresh 50/50 (with no SCA added). This will lower your SCA level by diluting the old coolant/SCA solution with new coolant.
If your 3-way Fleetguard test strip is showing a reading of Molybdate (scale on left side of chart), then the coolant was not replaced with the Gold, or it was not flushed completely when changed out. The Gold is a Nitrite-only coolant, meaning that zero Molybdate is present. And the Gold will not have 3.1 Units of SCA even when new (at best it will have minimum SCA protection).
