From personal experience I wouldn't even use a standard ethylene glycol coolant in an engine that has had OAT drained from it without flushing at least twice. Otherwise a soapy layer of 'stuff' will be produced and line all surfaces. It's not likely to do any harm, but hardly likely to be beneficial either. I'd just stick with one or the other or use a hybrid which is miscible with both. It is possible that your product is one of those.That said, I'd recommend not mixing them, it's usually best to switch oils / Antifreeze from empty wherever possible.