I can start of by saying I do not use oil additives in vehicles that are in relatively good shape and do not have mechanical issues that could potentially cost more that the vehicle is worth.
This said I have a friend that had a Saturn that the oil was milky. Drained the oil and coolant and added the head gasket fix snake oil stuff to it. He drove it another year before there was coolant in the oil again. I doubt the head gasket fixed itself and we know that since the issue came back it did not fix it long term. What we do know is that when it first started he could not afford a replacement vehicle and he had nothing to loose. When it went a year later he could and did replace the car.
If there is nothing to loose I am for trying the stuff. If it can be fixed cost effectively etc. then just fix it right.
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