What should be noted when lubricating a vehicle?

Your answer is correct because when lubricating a vehicle, it is important to first clean the lubrication nipples to prevent dirt and debris from entering the system, which could cause damage. Also, applying enough grease so that a visible layer forms ensures proper lubrication and protection of the parts. While it's true that old and new grease should not be mixed, this rule is less crucial during a routine lubrication compared to cleaning and applying sufficient grease. Following these steps helps maintain vehicle components and prevents premature wear.