Is Jake acting "in the scope of employment" or do his actions cause him to fall out of this area?

Generally, an employee owes the employer duties of performance and obedience. And under their duty of performance, there is an implied condition that employees will use reasonable diligence and skill in performing their work. A duty is also imposed on an employee to follow all lawful and clearly stated instructions of the employer. Any deviation from such instruction is a violation of that duty. Whenever instructions are not clearly stated, the employee can fulfill the duty of obedience by acting in good faith and in a manner reasonable under the circumstances.

Here, Herman has told Jake that he is "just supposed to change the oil..." and not check the brakes, tires, transmission, etc. So it would appear that Jake is violating his duties. However, Jake argues that "as a certified mechanic, there are standards that (he has) to live up to" and that his actions are reasonable under the circumstances.

Whether Jake is "acting in the scope of employment" is a fact question to be decided by a jury. Given the circumstances, and that the overriding reason that Jake is working on the cars in the first place is Herman's free oil change it would appear that he is within the scope of employment.

Is Herman responsible for Jake's injury?

Yes, Jake is covered under state worker's compensation laws. Under common law, employees injured on the job had to rely on contract law theories or tort law, and were often defeated on claims of contributory negligence or assumption of risk. Today, however, state and federal statutes have been passed to protect employees from the risk of accidental injury resulting from their employment. And in general, the right to recover worker's compensation benefits is predicted wholly on the existence of an employment