[rwarre]

I am getting small oil streaks on the top of my cowl and the windsheild. Is there a way to tell if the front oil seal is the culprit?

 

[Ralph Inkster]

Feel inside the back of the flywheel, if it's wet with oil, your front seal is leaking.

 

[jdeas]

Crank flange and flywheel

Three things can leak up there. Blade to hub, hub to crank, front seal.

Oil on the flywheel can be the front seal or (on a CS prop) the crank to hub O-ring but I would think that only leaking from a blade would result in oil outside the cowl.

 

[vic syracuse]

Actually, there are a few more places...

On the front of the engine there is usually a pipe thread plug fitting for the oil galley. It can leak as well. Sometimes they aren't tightened and sealed properly after a rebuild when that particualr fitting is used on initial runs.
As mentioned in another thread the seam of the engine can leak, too. And if you happen to have a front mounted prop governor, those seals can leak. The governors usuallyu need to be really tightened down hard to prevent leaking.

Vic

 

[Tom Martin]

A couple of other spots (no pun intended)

If your upper cowling/fuse joint is not perfectly tight, i.e. some bulging in flight, you can get spots from a loose dipstick tube, or even an oil filter that has not been tightened enough.