Reply To: Oil leak Great British Handcrafted Motorcycles › Forums › Spitfire – Bobber › Oil leak › Reply To: Oil leak 8 June 2022 at 10:01 #12090 Mal1259Member Hello, I have the same crankcase breather filter problem with my brand new bobber, can i ask what is the best oil to use for topping up if required? Cheers Mal.