What should be noted when lubricating a vehicle?

The answer you provided is correct because both points 1 and 2 are essential practices when lubricating a vehicle.

1. Cleaning lubrication nipples before applying lubricant is crucial to prevent contamination that could interfere with the lubrication process. Contaminants can lead to wear and damage within the vehicle's components.

2. A noticeable layer of grease should be visible, as this ensures that the parts are adequately lubricated. Insufficient lubrication can lead to increased friction and potential damage over time.

It's important to also consider point 3, which states that old and new grease should not be combined. This is critical because mixing different types of grease can lead to chemical reactions that may diminish the effectiveness of the lubricant and could cause failures in the lubrication system.

In summary, understanding and applying all these practices helps maintain the vehicle's mechanical integrity and ensures safe operation, which aligns with the regulations outlined in German traffic law regarding vehicle maintenance and safety.