I've used seafoam for years without problems. I wouldn't use it in the z yet since i still have low mileage. Most cars i use it on have over 130k on the ticker. I run a third of the can in the oil for a few miles then change the oil immediately since it thins it out. Another third in the intake manifold and the last third in the gas tank. It's helped a little on higher mileage cars restore some pep. Just my experience
