Why do you have to change synthetic oil?

If you own a car, it is important to know when to change the oil. If you do not do so, your engine will develop several issues. For instance, the oil can cause corrosion to the different engine parts. This will result in poor performance on the long run. You must refer to your car model to know how often you have to change the synthetic oil.

The oil itself never really wears out, but it's job is to pick up and suspend all the micro particles that wear off of the engine as it runs. The oil filter's job is to filter out and hold the larger particles when the oil circulates thru the oil filter. When you change your oil, the oil that is drained from the engine contains the suspended particles of contaminants, so they are removed from your engine. The oil filter also contains contaminants that will be removed with the filter. A new filter is filled with fresh oil and the proper amount of fresh oil is put into the engine. The used oil can actually be "refined" to remove all contaminants and recycled to become new oil again. It doesn't matter if it's conventional oil or synthetic oil, it's job is to prevent wear of the engine components and suspend the contaminants that do wear off of the engine's moving parts.

Additives break down, engine blowby and condensation contaminates the oil. Worn metal particles accumulate in the oil and increase engine wear.

bECAUSE IT GETS DIRTY AND BRAKES DOWN; JUST LIKE REAL OIL DOES.

Synthetic gets contaminated and breaks down just like regular oil.

I've known quite a few people with synthetic oil in their engines who will change the filter at 5K, top it off, and go another 5K before doing an oil/filter change - and they haven't had any problems with their cars.

Because synthetic oil gets dirty just like petroleum oil.

Because it gets dirty after 5,000 miles and the oil filter needs to be changed too.

Oil is designed to lubricate your vehicle and to absorb little impurities and little particles of metal from the moving parts in your engine you definitely want to get rid of those particles so they don't sandpaper your poor engine to death

Even if the oil never broke down, contaminants build-up within the oil which eventually turns it to sludge...

All oils get contaminated. That's mainly why you change it. Not because it's worn out. Sludge will form if oil is not changed.