WHY do we change our oil?

[merle&louise]

Why do we change our oil?


Does the oil break down?

Is synthetic better than conventional oil? Does it break down like regular oil?

Is it because the oil gets dirty? If so, can it be recycled?

Does it hold sulfuric acid from the diesel fuel burning under pressure or is that a myth?

How are the changing intervals determined?

[lewpopp]

Tuga,

I used to know the real answers to your question but time leaves some of the facts out.

I believe oil does not break down. The reason it is changed is that it keeps the dirt suspended in the molecules and not all is sifted out throught the filters. Users additives change a lot of the consistency of the original products. It's been 30 years since I was really abreast of the facts.

Let's go guys, let's hear it.

[JIM CHALOUPKA]

Here you go Tuga, read this and you will have some of it. ;):cool:

Notice the side articles as well!

http://www.gulfcoastfilters.com/Quaker%20State.htm

:)JIM

[adamdegraff]

Do I remember correctly a post form John saying that the additives in the oil get "used up" before the oil actually breaks down?

[merle&louise]

Here you go Tuga, read this and you will have some of it. ;):cool:

Notice the side articles as well!

http://www.gulfcoastfilters.com/Quaker%20State.htm

:)JIM

Good post, Jim. I read the article and it answered my questions. Thanks.

[sawdust_128]

Why do we change our oil?

Steel parts rubbing next/very near to each other will wear and overheat and can weld themselves together "SEIZED engine". Oil provides lubrication and prevents/slows this down to a minimum if properly used.

Does the oil break down?

It is a mixture of organic compounds which when exposed to heat will begin a process of decomposition. Oxygen exposure causes oxidation or a "burning" of the lighter components of the mixture.

Is synthetic better than conventional oil? Does it break down like regular oil?

The question here is better for what? They both accomplish the same thing, lubricate the moving parts, reduce heat production, effect heat transfer, and prevent moisture attack of the raw metal parts. One is man made and the other is a fractional distillation of a naturally occuring substance. Synthetic oil is still a mixture of organic compounds which behave and react just like their natural counterparts. The components in synthetic oils are generally selected to minimize the decomposition process. Which is why, very often, the change interval is longer for synthetics, but there is still a change interval.

Is it because the oil gets dirty? If so, can it be recycled?

Yes and yes. Most auto parts places have resevoir for capturing used motor oil. What the uses are for this when it is re-refined, I don't know.

Does it hold sulfuric acid from the diesel fuel burning under pressure or is that a myth?

I don't know about this one.

How are the changing intervals determined?

For an over-simplified explanation, it's like crash testing. They engineer the motor for a purpose, and functional life. Then they bench test them to see how they do. If the motor blows up/wears out too early, change the oil more often. They estimate an oil change interval to get the motor to meet the design expectations of the motor. Some manufacturers watch the records from the dealer service centers. They look at the time to fail on real life use products. They make recommendations based on these and many other types of data.