Tristan,

Look in to one of these: http://www.saikoumichi.com/product_line.html

This keeps vacuum on the crank case while storing the oil. With the 944, venting to atmosphere has been a problem, causing the engine front seals to leak. There are a few 944/951 guys that swear by them.

I don't have one yet but an getting ready to buy one.

Hope all is well

Tim