16 year owner of 2008 e85 Z4M w/ S54 motor. I’m a former flat rate dealer tech (not BMW) & do all my own work. I’m chasing down an oil leak.

Leak is on passenger side of motor. About 12,000 miles ago I removed the plastic stray & subframe tray & pressure washed everything down perfectly clean. I followed it for a while & kinda gave up on it - other stuff got in the way.

I had to remove both trays again & there is an oil leak. It’s bad enough some stuff is “wet” / grimey - but not bad enough you see drip marks in the ground. It seem like most of it is getting on plastic tray & mixing with dirt & just sticking there.

Pressure washed everything perfectly clean again. I bought a fluorescent oil dye leak kit to help diagnose.

It’s on passenger side, areas that are wet are passenger side: front of oil pan, back of oil pan, power steering lines (underneath right above drip tray), & block.

I replaced CPV valve w/ factory about 5 years ago going after similar/same oil leak & it seemed to fix it at them time. The problem is leak is not bad enough that it takes so long to show & I only drive the car ~ 5k miles a year. Dont need to add oil between yearly oil changes & car runs perfectly.

Honestly, before I cleaned everything, it looks like it’s leaking out of the back of the head by CPV. I think an oil leak at head gasket is pretty unlikely - but maybe not? It very well could be CPV again & it’s wet above that from oil blowing around. It’s 100% def not valve cover gasket. I’m pretty sure power steering lines are leaking at least slightly where they form a “U” above the plastic tray - but I don’t like to hang parts unless I’m sure something is bad.

• Do S54 head gaskets leak oil slightly on a healthy running car?

• Anything else leak oil on the S54 passenger side appearing to come form under / near the headers where you can’t really see? I’m thinking about ordering a boroscope to fish it under the headers to see what I can see.

• Have you seen oil slightly above CPV valve (closer to head gasket) of CPV is leaking?

Certain areas are wet above the oil pan so I’m thinking it’s not that or it’s a very minor contributor.

TIA