Changed my mind about premium coolant after a 6.7 Cummins tear down

I used to think any coolant was fine as long as it was the right color. Then I pulled apart a 6.7 Cummins last month that had been running the cheap green stuff for about 4 years. The cavitation damage on the cylinder liners was BAD, little pitting spots all over. The owner finally switched to the Fleetguard ES Compleat after that and the next tear down at 300k miles looked CLEAN. Has anyone else seen cavitation damage clear up after switching coolants?

2 comments

2 Comments

patricia3858d agoMost Upvoted

See it different honestly. The damage was already done by the time you found it from the green stuff, not like switching later fixed pitting that was already there. Those liners were probably going to look rough no matter what you put in after that point.

jackson.wesley8d ago

My buddy Dan runs a fleet of Ram 3500s for a logging outfit up in Bend. He had a 2018 tear down at 220k that looked exactly like that - pitting all over the liners from cheap coolant. Switched to the Fleetguard stuff and ran it another 180k miles. When he pulled that motor apart a few months ago the liners were smooth as glass, no new pitting at all. The original damage was still there but it didn't get worse. That was enough proof for me.