Found some smudges on the driver door leather, possibly fingerprints of a technician.

After I ID the prints, hunt down and reproach the perpetrator, what is the best product to clean the smudges without harming the leather?

Kinda looks like grease but honestly I'm not sure. Can only see them in full sunlight.

 

The best leather cleaner I've ever used is Dojo Juice Supernatural.
Just cleaned the (very shiny) steering wheel. It came up really nice. It stripped off 15 years of muck, and left the surface a nice matt finish.

 

There's a brand in the UK which got really high reviews in tests...I'll post the name later because I can't remember it. The best cleaners have two solutions. The first is a liquid cleaner which you use, let dry and evaporate etc, whilst the dirt comes off on your cleaning cloth. The second is a leather cream which nourishes and protects. The issue with single use products is they're cleaning and rubbing the dirt back in via the cream. Presuming they have some magic chemicals that try push the dirt out onto a cloth whilst the cream is going into the leather!

 

Nothing fancy, a bit of liquid hand soap and water should do the trick.

 

Thanks for the tips gents!