912ULS Oily Exhaust Discharge?

looks like an oil leak from inside the cowling not the exhaust...trace it back inside

Thanks. That was my first thought too, but the inside of the cowl looked and felt clean. Also no oil on the floor before the flight, but you may be right. The oil tank is also on that side. Haven't had a chance to get back to the hangar yet to investigate further.

I agree with Glenn.  Pull the cowlings, look for oil anywhere on the engine including around the oil filter.  Check the oil tank including drain plug, vent line, cap, and confirm your oil level is correct on the dipstick. All oil line connections tight?  Oil tank vent hose, is it routed properly and not exposed to the slipstream? Is the tank vent hose end end wet with oil? If all good clean it up well and do a ground run cowls off and inspect for leaks.  If none cowl up and a short flight, then cowls back off and inspect for leaks.  

Thanks to you both. Probably should have done all that before posting, but will as soon as I can get back to the hangar. 

 As Glenn and Jim suggested the exhaust had nothing to do with it. The Saf-Air quick-drain on the oil tank was weeping. Not enough to drip oil with the engine off, but enough to lose a very small amount when the engine was running. The O-rings in the valve are replaceable but I've ordered a new valve anyway. Next time I'll do a bit more investigating before posting.