I added Seafoam to the oil (M1 0W30 AFE) in my 02 Yukon XL. 5.3 LS engine, 175,000 miles. It has the common piston slap, a rather severe case.
Even hot it has a slight bit of it, sometimes I wonder if it is a lifter tap. The truck runs great though and hardly burns a drop of oil. The noises have remained the same for the past 15k, since I got it. After watching a page called Project Farm, seemingly do an unbiased test, Seafoam in the oil quieted down the valvetrain in the test truck. (Video below). Seafoam won't help piston slap but a lifter issue it may.
Prior to the addition of Seafoam, my oil was at 5300 miles and was a clear amber. I added 6-7 oz of Seafoam and put a couple hundred miles on a few days. No changes, aside from slightly darker oil on the dipstick. I had written it off as not effective. 5 more days and I'm past the 400-mile mark, planning to change the oil somewhat soon. I picked a girl up to get lunch and do a few other things. While I'm waiting for her to come outside I notice my hot idle oil pressure is down. About 4 pounds down. I can't trust the OEM gauge for perfect accuracy but it was lower than normal. I shut it off, check the oil, it's full and a bit darker. She comes outside while I've got the hood up wondering if everything is ok. I tell her I was just checking the oil since I was waiting so long...
We drive about 30 minutes and when I park my idle oil pressure is even lower than before, I'm at 23 instead of my usual 29. I get out and I can smell that hot engine smell as I walk past the front. Smells like when an older car that is running low on oil or a car with an electric radiator fan that isn't working and is running a bit warmer than usual. Also noticeable is all the metal noise "tinking" cooling down, like an old car or motorcycle would do. My coolant temp was normal. I feel fairly certain the Seafoam was creating extra friction or had thinned out the oil too much.
Eventually, I got it home and drained the oil, no debris came out, nothing suspect was left on the bottom of my clean drain pan.
PP 10w30 went in. Full heat soaked hot idle oil PSI is back to normal.
Perhaps it was coincidental, I'm fairly skeptical though. The engine was not liking something and if I didn't add the Seafoam I would have ran that oil for another 2000 miles easy.
Even hot it has a slight bit of it, sometimes I wonder if it is a lifter tap. The truck runs great though and hardly burns a drop of oil. The noises have remained the same for the past 15k, since I got it. After watching a page called Project Farm, seemingly do an unbiased test, Seafoam in the oil quieted down the valvetrain in the test truck. (Video below). Seafoam won't help piston slap but a lifter issue it may.
Prior to the addition of Seafoam, my oil was at 5300 miles and was a clear amber. I added 6-7 oz of Seafoam and put a couple hundred miles on a few days. No changes, aside from slightly darker oil on the dipstick. I had written it off as not effective. 5 more days and I'm past the 400-mile mark, planning to change the oil somewhat soon. I picked a girl up to get lunch and do a few other things. While I'm waiting for her to come outside I notice my hot idle oil pressure is down. About 4 pounds down. I can't trust the OEM gauge for perfect accuracy but it was lower than normal. I shut it off, check the oil, it's full and a bit darker. She comes outside while I've got the hood up wondering if everything is ok. I tell her I was just checking the oil since I was waiting so long...
We drive about 30 minutes and when I park my idle oil pressure is even lower than before, I'm at 23 instead of my usual 29. I get out and I can smell that hot engine smell as I walk past the front. Smells like when an older car that is running low on oil or a car with an electric radiator fan that isn't working and is running a bit warmer than usual. Also noticeable is all the metal noise "tinking" cooling down, like an old car or motorcycle would do. My coolant temp was normal. I feel fairly certain the Seafoam was creating extra friction or had thinned out the oil too much.
Eventually, I got it home and drained the oil, no debris came out, nothing suspect was left on the bottom of my clean drain pan.
PP 10w30 went in. Full heat soaked hot idle oil PSI is back to normal.
Perhaps it was coincidental, I'm fairly skeptical though. The engine was not liking something and if I didn't add the Seafoam I would have ran that oil for another 2000 miles easy.