I have used seafoam for years, and on lots of cars with over 200k. I just did a V10 Excursion the other weak, made a huge difference in the way it ran, it had 225k. I've done my E30, over 200k, my old CRX motor, over 200k, my integra, over 200k, and so on. I have never heard of seafoam hurting an engine (besides internet gossip), ever.