Carbon deposits will affect the quality of engine oil?

How does engine oil form carbon deposits in the cylinder? First, we need to understand how the oil lubricates and protects the engine cylinders. Most of the oil in the engine is transported to the friction surfaces by the oil pump (pressure lubrication), a small part of the oil is thrown onto the cylinder barrel wall by the bottom of the crankshaft balance weight (splash lubrication), and the cylinder barrel wall is lubricated by the oil contaminated by this.

There is a lot of oil on the wall of the cylinder barrel. We know that oil is a "flammable substance". If the "excess oil" is not scraped off, the oil in the cylinder will coke due to the high temperature. Therefore, the oil scraper ring of the piston ring plays the role of scraping the "excess oil", leaving only a very thin oil film on the cylinder barrel wall.

This layer of oil film is actually still attached to the cylinder wall when the gasoline in the cylinder is burning, and it is directly smoked by the high-temperature gas, evaporating, and leaving coking substances. In fact:

1. If the oil scraper ring of the piston has low efficiency and poor effect, then the thickness of the oil remaining on the cylinder wall will be thicker, so the amount of residue at high temperature will increase, that is, "fast carbon deposition", and Engine oil will also be consumed very quickly.

2. The second is that different engine oils have different formulas. Of course, the amount of "solids" remaining after high-temperature grilling will be more or less. In other words, the greater the amount of oil remaining "the faster the carbon deposition rate."

So the next question is: What kind of oil residue will be less? It's simple! Generally speaking, the high-temperature residue of fully synthetic engine oil is less than that of semi-synthetic oil, and semi-synthetic oil is less than mineral oil. Nowadays, mineral oil has basically withdrawn from the stage of history, and semi-synthetic motor oil has replaced the previous position of mineral oil, occupying the low-end field.

On the other hand, we can also judge the high temperature residue of the engine oil by observing the level of the engine oil. For example, the residual amount of SP grade oil is lower than SN-PLUS, and SN-PLUS is lower than SN, and the residual amount of C grade oil of European standard is lower than that of A/B grade. That is, the newer the engine oil, the less high-temperature residue.

Nowadays, because of the complete maturity of the production process of the 3 types of base oil, the output has increased greatly. The greater the output, the lower the cost. Therefore, the price of today's fully synthetic engine oil is getting cheaper, so the price advantage of semi-synthetic engine oil in the past is becoming less. Drivers can choose fully synthetic engine oil to control the speed of carbon deposits in the cylinder.