John Robertson said:
Inside my engine is like a sewing machine no crud at all thanks to
synthetic oil.
Oil removed during an oil change should appear dirty. If an oil is
doing its job properly, it should suspend dirt, metallic wear materials,
and unburned carbon. Therefore, when you change your oil it should look
much dirtier than it did when first added to the engine. An excellent
method for monitoring an oil¹s condition is through oil analysis, which
can be key to any preventive maintenance program. Oil analysis must be
conducted regularly to establish trends of operation. It provides
information on wear metals, viscosity integrity, fuel dilution, and air
intake system leaks, among other things. As a long-term preventive
maintenance tool, it will build a history of the engine¹s performance
and aid in the detection of possible problems before they become severe.
Technically, oil does not wear out. However, extended use causes an oils
additives to wear out or become depleted. For example, an ashless
dispersant aviation oil is designed to suspend dirt and metal particles
picked up from an aircraft engine. Eventually the oil will become
"over-suspended." The principal reason oil is changed at regular
intervals is to rid the engine of these suspended impurities. Old oil,
with a high degree of contaminants, can cause bearing corrosion and
deposit buildup. It can also get to the point where it will not suspend
the additional particles created during engine operation. This produces
particle buildup or sludge. Overworked oil will also result in the
depletion of its other additives. The result is that it will be unable
to perform with the benefits the additives were designed to provide.
[
http://www.swaviator.com/html/issueja02/Hangar7802.html ]
By the way, how long have you been repairing sewing machines? Do you
tear down your car engine in your sewing machine repair shop?