I recently seafoamed my 97 Tahoe, with the 5.7 Vortec. It has 137k on it. I first put in around 6oz through the brake vacuum line, slowing letting the engine ingest it. As it was being absorbed, clouds of smelly smoke started coming out the tail pipe, obviously it was starting to work immediately. I ran the engine at a mid-to high rpm idle for around five minutes. More smoke. About a week later, I put the remainder into the crankcase. Now, let me backtrack a bit. I was experiencing a check engine light, throwing a crankcase to camshaft position error. I had a noisy lifter. I seafoamed the oil. I then had to replace the distributor due to the fact the drive gear was starting to shear off. Ok, so new distributor, seafoam in the crankcase and now, engine light off and lifter noise gone. I'll be doing a oil change this weekend and plan to add a quart of Mystery oil and then change it again in another 1k miles. So I would have to say, if you apply the Seafoam as directed or recommended, you are gtg.