A RatStang Exclusive
Synthetics vs Conventional
First you need to understand what happens to make an oil "Bad".
Oil does not "Wear Out" and go bad. Instead what happens is the
additives get "used up" or rather change chemical properties.
The change is caused by heat and heat is caused by friction.
Synthetic oils are atomically smaller particles than conventional oil
particles. Like the old commercial said "Think of it a small ball bearings".
The smaller particles will be able to occupy smaller voids than bigger
particles. This reduces the contact of the engine materials with each
other thus friction is reduced and heat is reduced.
The end result is the additives last longer because the heat does not
change the chemical properties of the additives.
The other result is that since contact is reduced Wear is also reduced.
As mentioned in an earlier post Paraffin is used as a base for many oils.
That is what causes Sludge.
This is false.
What happens to form sludge is the oil suspends the particles (carbon, metal, other contaminates) in the oil to carry it to the filter. The filter
will remove these particles only down to a certain size. The remainder are reintroduced into the engine in the oil. The filter also has a capacity in which it can hold. The oil reaches a saturation point and can no longer suspend the particles and they begin to settle out of the oil. This is Sludge.
So why use paraffin in oil?
Paraffin will hold more particles than the Naphtha based oils.
It appears to Sludge more because once the saturation point is reached the
depositing is more prevalent.
So what about the Additives, What are they?
Additives are the anti-foaming, anti-separation, anti carbon, and the agents that suspend the particles in the oil.
Once these are saturated or used in the case of the foaming and carbon agents the oil is "Bad".
Since the synthetic reduces the wear and friction thus reducing the contaminates the oil can last longer.
But even a synthetic will saturate and use the additives over time.
That is why even if you run a synthetic like AMS Oil you still need to change the filter even if you don't change the oil. And after time you need to change the oil because the additives are used up.