Narrative:

Climbing VFR with climb power above a scattered layer monitoring adsb traffic on garmin 430 and ipad using foreflight at approximately 6500 ft MSL; I noticed an extreme oil leak on the left engine. I observed no traffic conflicts visually or on the adsb displays. I immediately turned back towards [departure airport]; reduced power; and started a descent while simultaneously [advising] ATC and requesting an IFR clearance back to [departure airport]. ATC asked the nature of the event; I replied; extreme oil leak on left engine. ATC issued IFR clearance to [departure airport] and assigned a heading of 270. I responded 'unable; request direct.' ATC gave me a direct clearance and clearance to descend at pilot's discretion to 2000. I acknowledged clearance. At some point I was descending through the clouds; I asked for vectors because I had not yet had time to reprogram my GPS. ATC gave me a vector and offered an alternative landing site. I proceeded to [departure airport]; did a visual approach and canceled my IFR clearance in the air. ATC requested that I call them after landing to ensure that I landed safely. I announced my position and landing intentions on CTAF. Someone responded asking if I needed assistance. I replied negative. I landed without incident; taxied toward my hangar and had my aircraft towed to the maintenance shop. I called approach as requested and provided more details on the event; my name; and pilot certificate number. The FAA visited the shop 2 days later to inspect my plane. I commend ATC on their professionalism and assistance.upon reviewing the incident; I do not believe that I violated any clearances or fars. 1. I was receiving flight following so I did not need to locate a frequency and contact ATC.2. I acted decisively (within seconds) to [advise ATC]; request an IFR clearance; establish a descent and turn towards the most suitable airport.3. I asserted my pilot in command authority and declined a heading clearance that took me farther from the most direct route to [departure airport].3. I utilized ATC as a resource for a vector because it was quicker than reprogramming the GPS at that moment. My 25 years of flying experience and annual recurrent training gave me the knowledge and experience to execute the items above.4. While descending and turning in the clouds; I found that I was descending at 2;000 feet per minute and I was in a bank in excess of 45 degrees. I reduced the bank to 30 degrees and the descent to 1000 feet per minute. This was unintended and could have resulted in a more serious unusual attitude if I had not corrected in a short period of time. I believe that this was caused by the stress of the situation and my failure to properly monitor the attitude indicator in the turn. I was preoccupied with turning to the most direct heading and was acting in a rushed manner when I should have remained calmer.reviewing my performance and completing this form as it relates to my event was a valuable training experience and has made to a safer and more experienced pilot.

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Original NASA ASRS Text

Title: C340 pilot reported returning to the departure airport after observing an oil leak from the left engine.

Narrative: Climbing VFR with climb power above a scattered layer monitoring ADSB traffic on Garmin 430 and iPad using ForeFlight at approximately 6500 ft MSL; I noticed an extreme oil leak on the left engine. I observed no traffic conflicts visually or on the ADSB displays. I immediately turned back towards [departure airport]; reduced power; and started a descent while simultaneously [advising] ATC and requesting an IFR clearance back to [departure airport]. ATC asked the nature of the event; I replied; extreme oil leak on left engine. ATC issued IFR clearance to [departure airport] and assigned a heading of 270. I responded 'Unable; request direct.' ATC gave me a direct clearance and clearance to descend at pilot's discretion to 2000. I acknowledged clearance. At some point I was descending through the clouds; I asked for vectors because I had not yet had time to reprogram my GPS. ATC gave me a vector and offered an alternative landing site. I proceeded to [departure airport]; did a visual approach and canceled my IFR clearance in the air. ATC requested that I call them after landing to ensure that I landed safely. I announced my position and landing intentions on CTAF. Someone responded asking if I needed assistance. I replied negative. I landed without incident; taxied toward my hangar and had my aircraft towed to the maintenance shop. I called Approach as requested and provided more details on the event; my name; and pilot certificate number. The FAA visited the shop 2 days later to inspect my plane. I commend ATC on their professionalism and assistance.Upon reviewing the incident; I do not believe that I violated any clearances or FARs. 1. I was receiving flight following so I did not need to locate a frequency and contact ATC.2. I acted decisively (within seconds) to [advise ATC]; request an IFR clearance; establish a descent and turn towards the most suitable airport.3. I asserted my Pilot in Command authority and declined a heading clearance that took me farther from the most direct route to [departure airport].3. I utilized ATC as a resource for a vector because it was quicker than reprogramming the GPS at that moment. My 25 years of flying experience and annual recurrent training gave me the knowledge and experience to execute the items above.4. While descending and turning in the clouds; I found that I was descending at 2;000 feet per minute and I was in a bank in excess of 45 degrees. I reduced the bank to 30 degrees and the descent to 1000 feet per minute. This was unintended and could have resulted in a more serious unusual attitude if I had not corrected in a short period of time. I believe that this was caused by the stress of the situation and my failure to properly monitor the attitude indicator in the turn. I was preoccupied with turning to the most direct heading and was acting in a rushed manner when I should have remained calmer.Reviewing my performance and completing this form as it relates to my event was a valuable training experience and has made to a safer and more experienced pilot.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.