Something similar happened to me. Climbing out of Lydd on an IMC exercise, passing 2500', the crankshaft seal decided to move forward and thus dump a lot of oil over the TB 10. I immediately turned back towards the airfield, (3.5nm) ,trimmed for best glide and throttled back to idle. Words to ATC, "by the way it's a PAN call"! The oil loss decreased and I managed to find one quick burst of power and made the threshold , using the side window as a landing visual reference. A quick tow to the back of the hangar. No damage to the engine , in fact we had 3qts remaining .Prop. off and seal changed. The aircraft then left with the owner back to its base at Biggin. Only paperwork, an MOR. Back home to a stiff whiskey and no medals!