I don’t know whether it is the addition of detergents that causes oil to carry around “wear particles” (eg bits of metal, some microscopic) but it is a fact that when used oil is analysed (which is done regularly by large fleet operators) the level of wear particles present in the oil is measured, as this provides info on how often to change the oil and in some cases impending disaster.
Without any basis for saying so in any given situation I think a detergent oil would be carrying round (aka suspending) more wear particles than a non detergent oil, and that’s why it is generally accepted (and not just my opinion) that it’s important to use detergent oils in combination with a filter.
Quite correct
FWIW I was lucky enough to be taught for a single term by Vince manners who at that time was head of the X-ray diffraction analysis team at the Defense Standards lab in Alexandria NSW.
Even more luck that when he found out I was unemployed at the time he swung me a temporary position as a lab tech in one of his teams .
This was back in the early 70's before the end of the Vietnam war and the subsequent renaming everything associated with the was and the slashing of budgets.
The DSL became the Materials Research lab but basically did the same work with around 10% of the staff & funding.
Anyway my particular job was to prepare oil samples for XRD .and then to sift through the results looking for known Millers Indicies for the actual alloys that were in the engines .
Vince pioneered this work which built on the previous work of the DSL & CSIRO who pioneered the use of chromotography to determine what METALS were present in an oil sample and later on the actual percentages of these metals.
This is what is done by most oil labs now days as it is cheap & very reliable but generally uses atomic adsorbtion rather than strait chromotography as it is more accurate & requires less sample preparation.
However what it does not tell you is weather the iron came from the cylinder lining, the cams, the rockers , the crank, a compression ring, an oil ring , a bearing or any other iron based part in the engine.
However by using XRD you can tell exactly which alloys the wear particles are made from and also how much is in there.
This data was then plotted against actual measured wear of individual parts during a routine engine strip & examination.
In those days the aim was to corelate these so to eventually replace the fixed service hours strip down which is both expensive and does damage to the engines.
It was proven to work and be highly accurate before the whole project got dropped and the team sacked , most of which went to the USA to join oil research teams or set up to do the analysis themselves , remembering in those days XRD machines were worth multi millions .
Wear particles in oil are measured in nanometers & picometers so that makes them sub microscopic.
It should come as no surprise that near 90% of the particulates that contaminate the oil is plain old carbon and that is formed inside the combustion chamber & on the exhaust valve .
From there it has a torturious path to end up in the crank.
If you stop to have a good think about where the carbon deposits are formed and how they are transported around the engine .
Some will adhere to the cylinder wall and be scraped off by the oil ring then drop to the sump. probably after being tossed around inside the engine a few times by the various moving parts .
It then has to pass through the sump gauze, then not drop to the bottom of the oil tank, pass through the output screen on the oil tank then through the oil pump to be spun off & held by the sludge trap . Quite a long trip .
