The viscosity of high quality engine oils will change only slightly during normal use. Sometimes, the driver finds that the oil becomes as thick as asphalt after a period of use. Why is this?

Excluding the possibility of using inferior oil, the main cause of this phenomenon is usually the high temperature mixture in the combustion chamber coming into contact with the lubricating oil and carrying large amounts of soot, in which case the lubricating oil is subjected to high temperatures far beyond normal operating conditions.

The main reasons for gas channeling are as follows:

1. The gap between piston, piston ring group and cylinder wall is too large (may be caused by wear, ring matching, ring stuck, foreign body invasion and other reasons), and the mixture of high temperature and high pressure will enter the crankcase through the gap in the power stroke.

2. The combustible gas enters the crankcase through the excessive gap between the valve and the valve guide, or the excessive gap at the failed valve seal.

If the car does not replace the oil in time for a long time, with the generation of engine wear and sediment, as well as the reduction of oil caused by its own consumption, its combined effect will lead to the increase of oil viscosity, and in many cases, even found coking material.

The phenomenon of "oil becoming bitumen" mostly occurs in some operational diesel vehicles with poor maintenance. Due to the loss of oil liquidity caused by lubrication failure, light burning shaft holding tile, heavy engine scrapped. In fact, "do not miscut wood", to prevent the occurrence of the above problems, the key is to choose good oil, regular maintenance of the engine (such as regular inspection of the engine, change the oil, change the filter, etc.).