[kbrandsma]

When the AOS goes it can cause the Oil filler tubes to expand and contract and eventually fail. This failure will cause oil to pool on top of the engine on the passenger side. Check some of the threads on this site by searching oil filler tubes. If your AOS is replaced you should also replace the J tube which connects the AOS to the throttle body(TB.) You can remove your J filler tube at the TB and see if their is any accumulation of Oil (a sign of a bad AOS.) Good luck!