Oil on spark plug

My brother went to dealer and was told that his 120k mile Sequoia needed all new fluids, and new spark plugs.

He didnt want to pay the money, so decided to do himself.

He replaced all the spark plugs, but when he removed one of them, the base was covered in oil. The ceramic part.

Is this something he needs to worry too much about?

Sorry, no pictures. Thanks

 

I wouldn't worry but I would look into the cause. A small leak today will turn into a bigger soon.
If is the ceramic that is oily only, then most likely is the spark plug tube seal or the valve cover seal.

 

We have a similar issue with oil in spark plugs, can it we do this or need to take into dear shop for repair?