What should be noted when lubricating a vehicle?

The correct combination of choices emphasizes the importance of proper lubrication procedures for vehicle maintenance.

Choice 1, regarding the necessity of cleaning lubrication nipples before applying lubricant, is crucial. This step ensures no contaminants interfere with the lubrication process, which could otherwise lead to inadequate lubrication and potential damage.

Choice 2 highlights that a noticeable layer of grease should be visible after application. This visibility indicates that the lubricant has been properly applied and can effectively reduce friction between moving parts.

Choice 3, while true, is not part of your selected answer. It addresses the issue of not combining old and new grease. Mixing different types of grease can create chemical reactions that may reduce the effectiveness of lubrication, ultimately harming the vehicle's components.

In summary, adhering to these guidelines ensures optimal vehicle performance and longevity, which aligns with best practices outlined in German traffic regulations regarding vehicle maintenance.