Last week, I had a local shop change the manual transmission fluid and differential fluid. I didn't use the dealership, because I didn't want to wait for over an hour. Their price was rediculous too. I did buy 4 quarts Nissan GL4, and I told the shop to use it for the transmission. They added synthetic GL5 to the differential.
The car drives fine, but I occasionally smell something. I can't tell if it is electrical or burnt oil. I looked under the car. I don't see any oil spilling. I did see two wires near the transmission.
So, what do yall think it is?
-gear oil spilled on the exhaust that is still burning off
-leaking oil from an overfilled transmission
-burning plastic from a displaced wire that is touching the exhaust pipe

 

Get underneath and check on a lift but diff fluid is really nasty smelling like rotten fart and eggs. It took like 3-4 days for the smell to leave my cabin since I had the window rolled down during diff fluid swap. Check to see if you see any leaking fluids or if you somehow have a bag or something stuck to your exhaust pipe from the road. Take it back to the shop that did the work and let them know your findings.