smelling the slight wiff of burnt oil i started looking, not under hood
oil on exaust under car in rear leads me to....
turns out there is a differential leak, shows itself under the rear differential mount which i don't think has fluid to leak out...so it MUST be the diff, but where and how and can i fix this, have you encountered this before, etc...? ap2 04 81 k miles

 

further research finds diff mounts are fluid filled i will bet this is what i found, lots of work ahead any help you can be go ahead and respond...

 

When diff mounts explode, they look like a murder scene. Get under there and take a closer look -- yes, you're correct, they are fluid-filled.

If you're handy with tools, buy OEM and you can replace them yourself -- this shows most of the steps: https://www.s2ki.com/2010/06/05/diy-...lation-review/ -- refer to your factory manual for torque specs.

 

Piece of cake to do. Thankfully the subframe has captive nuts for the mounts. Just pop off some exhaust hangers unbolt the sway bar bushings, and swing it out of the way. Then you can pop off the mounts, it's usually the driver's side mount that goes bad. Which incidentally is the easier one to swap out. They break when you can't and don't rev match on downshifts, ditto for motor mounts.

 

 

thank you all for the feedback, will surely check rear of trans...the leak appears to be from drivers side, if this is the culprit i will go with new front and rear...the left side one is covered with oil and actually dripping and the exhaust has oil stains on it...yes need to look further....

 

further investigation with car lifted in rear...diff is clean, rear of driveshaft is clean...oil has no odor and is very thin and black, i think it is the rear diff mount, so i think i will go with neoprene filled ones from after market. any thoughts??

 

https://www.s2ki.com/forums/s2000-un.../#post21302580

 

I did not want a harder ride so i choose oem mounts, not neoprene or plastic filled which are more for track use....ok, my final experience::
diff mount on drivers side leaked onto exhaust and i smelled it and found the leak
its not oil but it's black. these mounts, 2 identical front and two rear/right and left.
there are excellent youtube videos of how to and how to remove oem exhaust.
my car is oem, 81,000 miles , 2004, original owner, original clutch so you know it's vintage driven .
i believe this is a wear item and not dependent on how you shift or how old it is, they just harden and crack and loose fluid.

about 4 hours time which included getting car on 4 jack stands, home depo to get a replacement/fix exhaust stud and bolt, it works, no gasket either, just fits nicely, and bleeding all 4 brakes.

car is smoother on freeway, shifts seems more positive. job done

how you can tell, look underneath your car, where the exhaust goes from single to dual, the y, near the diff, under the diff, right or left side black water based and no oil liquid has spilled onto your exhaust

cost, majestic honda comes through in a week, about $290.00 for all 4, you need to get a left and a right rear and they are marked, and two identical front mounts
Oh, while under the car i checked out ,exhaust ,driveline, it is porschesque in quality, and it is clean, no oil or fluid the diff you could eat off...it's parked in a garage that's most likely why....so if you are out all the time and have few miles on your car you might look at these things.
no other mounts were damaged, but the passenger side rear was cracking and would loose fluid soon i am guessing, fronts looked fine.

 

Only the driver's side mount goes bad. It's the only one I changed in 180k miles. Cost me $90 shipped.