I got interested in varnish for some reason and was reading some of the old threads referring to other thread ...
The following are from knowledgeable bitog members and were not disputed (at the time) and I am basically summarizing it here:
I'm trying to get to the bottom of it and have a few broad and related questions based on the above summary (facts?). I could have combined them into one question I have in mind but let's try this:
Q1:
If synthetic oils don't hold contaminants well, why are they known to be better at sludge control? Is the synthetic oil capability to carry/suspend sludge contaminants different or higher than it's capacity to contain varnish?
Q2:
Sounds like varnish and sludge are different contaminants and the capacity to "contain" them is also different but the "precursor" thing (refer to #1 above) is confusing me. Does precursor mean it's a sequence of events (varnish first then sludge) or are they independent processes or chemical reactions?
Q3:
Is it possible to have sludge without varnish? For example with group II oil?
Q4:
Related to Q3.
Sounds like with synthetic (or group 3+ or pao), if you have sludge then you should definitely have varnish since "synthetics" have a relatively lower capacity to contain varnish. No?
Have you seen an engine using syn (e.g. pao) that has sludge but no varnish?
btw as I mentioned, my summary was collected from posts by knowledgeable members (@ChemLabNL , @OVERKILL , @Gokhan , I think @Shannow and others) and hope I didn't take them out of context.
Thanks!
The following are from knowledgeable bitog members and were not disputed (at the time) and I am basically summarizing it here:
- Varnish is the precursor to sludge. It is a sticky layer of precipitate that indicates that the contaminant carrying capacity of the lubricant was exceeded.
- Saturated ("synthetic") oils have very low contaminant carrying capacity.
- Group 3 and higher (4, pao, etc.) don't hold contaminants as well and have a limited capacity and need to be changed frequently.
- In sequence VG varnish test, PAO barely met the minimum 9.0 merits and GTL only scored slightly higher.
- Use Group II oils if you want to control varnish.
- keep oci short even with full synthetic.
I'm trying to get to the bottom of it and have a few broad and related questions based on the above summary (facts?). I could have combined them into one question I have in mind but let's try this:
Q1:
If synthetic oils don't hold contaminants well, why are they known to be better at sludge control? Is the synthetic oil capability to carry/suspend sludge contaminants different or higher than it's capacity to contain varnish?
Q2:
Sounds like varnish and sludge are different contaminants and the capacity to "contain" them is also different but the "precursor" thing (refer to #1 above) is confusing me. Does precursor mean it's a sequence of events (varnish first then sludge) or are they independent processes or chemical reactions?
Q3:
Is it possible to have sludge without varnish? For example with group II oil?
Q4:
Related to Q3.
Sounds like with synthetic (or group 3+ or pao), if you have sludge then you should definitely have varnish since "synthetics" have a relatively lower capacity to contain varnish. No?
Have you seen an engine using syn (e.g. pao) that has sludge but no varnish?
btw as I mentioned, my summary was collected from posts by knowledgeable members (@ChemLabNL , @OVERKILL , @Gokhan , I think @Shannow and others) and hope I didn't take them out of context.
Thanks!