Oil losses could threaten the performance of the engine. If leaking easy to know. So it looks complicated issue if oil shrinkage but no signs of leaking, though this question is easy.

Making car engine longevity among others to maintain the volume of engine oil such as manufacturer’s recommendations, volume could be shrinking due to burning [...]

How the importance of the engine coolant can we see from the following stories and articles.
This is the story of a friend and his favorite vehicle. Tiny car was treated seriously. Never forget, how busy, to check the major car fluids, including engine coolant. Through the reservoir near the radiator, he could see if it [...]