HD oils = clean ring pack?

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Oct 11, 2002
Colorado Springs
Does the use of heavy duty mixed fleet oil have the ability to clean out pre-existing deposits in ring packs? Or do they simply not create any buildup once the ring packs have been cleaned?
I don't think any oil will completely clean a dirty ringpack. This is where Auto-RX and LC excell. Most oils tend to supress or minimize buildup in the ringpack. Sludge, Carbon and ash deposits are the two main causes of ring sticking.
The newer HD diesel oils, especially the CF-4 and higher oils, are specially formulated to deal with "top grove fill." Top grove fill is when oil breaks down and leaves deposits behind in the ring land. The top ring especially will at first stick, then break. This quickly leads to massive oil consumption, bore polishing, then failure. I believe Top Grove Fill is set at 15%, though many better HDEO's test at less than half the allowable. I suppose a good synthetic HDEO might slowly clean deposits, but for excessive deposits a proper engine flush is needed. Jerry
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