We change oil of many cars per day. When the old oil comes out from the car, it tells everything indeed.
The clients who are regularly using Havoline & Total & even toyota's tin pack oils, when they come for change (mostly before the recommended change intervals), the oils are quite adhesive, dense, sticky, smelly (burning smell), reduced, etc. The health of the drained oil usually give general review about its performance.
And when the customers come for change who are using PTT, Kixx, ZIC ow & xq, etc. the drained oil seems quite healthy. Despite its color, it still has lubrication, no slug or dense, drains in seconds, full in quantity, etc. etc. And hence we know that oil condition is good enough.
And also we carefully note the comments from the customer about their experiences.
