Oil leak... cold weather?
 

So I just noticed my 3rd gen 305 1990 rs camaro is leaking oil..

It's not from the pan, plug or filter. I can see the stream coming down from the front of the pan.. dripping under the plug. If i had to guess.. i would say it is coming from the driver side. Could be the back of the valve cover..
I will get this checked. It looks a little wet behind the driver side valve cover.
Only leaks when it's hot.

My question is.. it is now getting into some colder weather. I would say a good 10-15 degree difference.
Could 10w30 be the cause? should i switch to 10w40 for the winter??

actually you got it bass ackwards. 10w40 in the summer and 10w30w in the winter

Outside air temp has little to do with oil leaks, once the engine is at running temp the thickness of the oil is determined by the engine temp. But even if it wasn't, it makes no sense to go to a heavier viscosity oil in cold weather.

Thanks guys. I felt this question seemed a little rhetorical.