Question: I recently changed the engine oil . I noticed that there is a small layer of foam on top of the oil level in the sight glass when I switch off the engine. The layer disappears after a while. I have done 4 rides (20km each) and it does it every time. Any thoughts?
Spectro Oils Answer: The foam you see forming on the top of the oil is normal, and does not in any way effect performance. When oil is cool it tends to produce a slight foam on the surface until operating temp is reached. As the oil temperature rises (normal operating temp 170-220 degrees F), the oil viscosity becomes lighter and the bubbles trapped on top will “pop” and the foam you see will disappear. The film strength of the oil at colder temps will trap air at the top of the oil reservoir, this is why you see a small layer of foam. This is different from oil “foaming” which is air trapped in the entire body of oil and is bad for oil and engine performance. Oil saturated with air will cause “cavitations”, erratic oil pressure, oil overheating and possible starvation of oil to engine components. Poor quality oils are prone to foaming when hot or stressed. Spectro Performance Oils.