The various outcomes that are possible include:

Changing oil on engine owned by someone else

If the shop were just changing the oil, only the actual work would be excluded because of exclusion l.—and then only after the work was completed and the engine turned over to the customer. So, if the entire engine were damaged because of the missing plug, only the oil change and the plug would be excluded.

There would be different reasoning if, for example, the mechanic had not yet finished the job, started the engine, and the engine seized. We then would have to review exclusion j., damage to property. If the damage occurred during the repair process, the damage probably would not be covered because 1) the engine (personal property) was in the care, custody, or control of the mechanic and 2) the engine would have to be restored, repaired, or replaced because the work was incorrectly performed on it.

Rebuilding or reconditioning entire engine

If the entire engine were being reconditioned or rebuilt and subsequently was ruined by the lack of oil, the entire engine would be excluded. This is because the work encompasses the entire engine and not just the oil reservoir. Again, exclusion l. applies if the work has been completed and the customer has taken possession of it.

Modifying engines for resale

If the shop actually owned the engine and was repairing or reconfiguring it for resale, exclusion k., damage to your product, would apply. The engine would be the insured's product, and the property damage would arise "out of it or any part of it." Again, if the damage occurred during the repair process, exclusion j., damage to property, would have to be reviewed for its application.

Many courts have taken positions on just what your work and your product encompass, and review specific details of each case to arrive at their rulings.