Engine Oil Change Duration regarding with respect to Engine Oil Top Up

We all know that engine oil are of 3 types namely 1. Mineral Oil 2. Semi-Synthetic Oil 3. Synthetic Oil. Right. And their drain intervals 2000-2500 kms, 3000-4000 kms, After 6000 kms correspondingly.

And we all have plenty of engine oil manufacturers with a wide range of oil grading which is further diversified as single grade 10W and multi grade oil ex. 10W-50 where we know that 10W describes the oil viscosity at cold temperature and 50 describes the oil viscosity at 100 degree centigrade or 212 Fahrenheit

The engine oil over a period of time and distance traveled will lower the volume of the engine oil in engine. If the engine oil is in good condition or quality and low in volume then we need to add the engine oil to the engine oil recommended capacity for that engine as far as the vehicle is concerned. As engine oil capacity differs from one vehicle to other. Depends upon the vehicle manufacturer’s specification. On other side in some case, lowering in the engine oil volume indicates the major mechanical defect or issue too!!

Also, engine oil with correlation to the mileage of the vehicle is concerned is greatly affected over the period of time and with distance traveled, as it reduces the quality of the engine oil since its running on the engine or being responsible for functioning of the engine.

Secondly, over a period of time the engine oil is also contaminated the combustion residues, lower quality fuel, minuscule particles accumulated from the wear and tear of the engine components over a period of time also reduces the quality of the engine oil. Thereby the mileage is also lowered relatively over a period of time and distance.

My question is, how one can identify irrespective of the type or grade or rating of the engine oil is concerned that this is the time to change my engine oil. As with, respect to time or distance traveled or performance in relation to mileage?

Thank You!!