I changed my plugs today and noticed a little oil coating on my 2nd coil but no oil on the spark plug. I looked around and did not notice any oil leaks from the valve cover seal or under the car. I check the oil level on the dip stick a day it looked the same as when I changed the oil a few weeks ago. Also no misfires codes. I Wondering if it’s the valve seals? What it might cost and if it could wait for me to dl the timing belt in another 50k Miles. And has any one replaced them.