Not sure what oil was in it but it was due a change I used 0/40 mobile 1. The filter was paper and still in reasonable shape replaced with the mann fleece. I've considered the oil change could have been a factor. Due to being over 100k I may want to try 5/40. I am finding it odd i have no sound in my block but guess we will see when i get the covers off. I will definitely update as I learn more this site has a wealth of info I'm happy to add what I can for others.