Long OCI vs engine cleanliness

[JohnBrowning]

Lobo11, What do you think varnish does to seals? Seal failure is the number one cause of long term dirt ingestion into an engine. Labor to replace seals is also not cheap. That layer or varnish is also like a constant oxidation force going on inside the engine. It is constantly working against the oil anti-oxidant propertys shortening the life of the oil. Varnish can also cause localized hot spots to develop. If you have varnish or Laqueer in an engine you are also getting close to haveing a sludge issue.

Synthetics reduce the chances of sludge of varnish but they do not elimanate the issue. The area's that benifits the most from synthetics is the ring pack and pick up screen.

 

[Dr. T]

The problem I have is that we've already discussed here that used oil analysis don't tell you much about the state of engine cleanliness. In other words, from my understanding, you can have a good/great used oil analysis and yet the engine is developing sludge/varnish.

All I can say (from my experience) is that if you want to do OCI's longer than 3k (and you should with synthetics) the visible condition of the oil combined with quantity of consumption may be as good an indicator as a performing a used oil analysis.

As a rule of thumb, if your oil is black, it's most likely cooked...change it. If this is occuring at or less than 3k...you need an oil with more cojones...not shorter intervals.

 

[haley10]

quote:

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Originally posted by Dr. T:
The problem I have is that we've already discussed here that used oil analysis don't tell you much about the state of engine cleanliness. In other words, from my understanding, you can have a good/great used oil analysis and yet the engine is developing sludge/varnish.

All I can say (from my experience) is that if you want to do OCI's longer than 3k (and you should with synthetics) the visible condition of the oil combined with quantity of consumption may be as good an indicator as a performing a used oil analysis.

As a rule of thumb, if your oil is black, it's most likely cooked...change it. If this is occuring at or less than 3k...you need an oil with more cojones...not shorter intervals.

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I tend to also look at the consumption issue. Right or wrong, I don't like adding much makeup. I tend to avoid the oils that disappear more, synthetic or not. I figure I probably don't have a sludged engine if it's staying in grade and consumption is minimal.