Planning a trip up that way Memorial Day weekend.  Will be fishing East Hickory and want to give Oil creek a go.  I have never fished Oil before any information on what hatches are usually on Oil around that time and how are the 2 DHALO areas to fish would be greatly appreciated.

Stone flies and caddis.. evening hatches can be crazy. I did well around Petroleum Center a few years back.

Good mayfly hatches but I've found you just can't go wrong with a muddler minnow. Poor water conditions last fall should allow a good holdover of trout west of Petroleum Center.  

How is Buffalo Creek?? Thinking the traveling the 2end week in June. Are the Fish big and easy to catch with the warm water? Rapalas or flys?

southern trout
How is Buffalo Creek?? Thinking the traveling the 2end week in June. Are the Fish big and easy to catch with the warm water? Rapalas or flys?

Buffalo on the Butler/Armstrong line? There should be some fish. Its part of the Keystone Select waters, so PFBC and local club adds some good size fish. Just use whatever trout lures you normally use.

Oil Creek in late May early June.
On top Caddis, and Light Cahill. I've seen some epic Cahill hatches.
Emergers in Caddis, sulfur, hares hear soft hackle
Down low with Caddis, stones, wooly bugger in olive, black, white.
Go to Mikes Oil Creek Fly shop and he can lead you in right direction. 
 
Ive witnessed some areas with multiple feeding lanes one might like caddis, one likes Lt Cahill. Right fly in right lane makes all difference. 
 
Also, in mornings, swinging caddis emergers or soft hackles through riffles can be fun and easy.
I hope to get back there myself this year. Good luck.
 
Rickerd

Buffalo creek can be a lot of fun with soft hackles in or near the riffles.  The water can get a little warm in summer but can be good early morning and late afternoon/evening.  I haven't noticed a big mayfly population but lots of caddis and midges.  It does get hit hard being so close to Butler and Kittaning but has a lot of fish and occasionally have seen a beaver prowling around (NO NOT THAT ONE).   Black soft hackles and wets always seem to produce good throughout the day.  Good luck southern trout.  Oh one more thing It has a silty bottom in a lot of places so lace up your boots tight, thought I would lose mine once or twice lol. 

Thanks to all that have replied I appreciate the info.  I will stop in that fly shop thanks Rickerd.