I'm having my engine rebuilt and they took my transaxle apart to replace 3rd gear syncro It would grind occasionally. While they had it apart the trans was caked with bluish goop. I used lightweight Redline shockproof for 10 years and only lately switched to Reline MTL which really improved shifting. They used many cans of solvent to clean out the sludge from the lightweight lube. The filter was completely clogged with it. KellyMoss said they noticed this with their race cars also.They recommend MTL.
Redline has stopped recommending Shockproof for 355s... http://www.ferrarichat.com/forum/145016550-post22.html
Redline 75w90ns is the correct oil. This is different to redline shockproof which contains some sort of "emulsion" held in suspension in the oil. It provides a cushioning to the gears under really high pressure applications but is only suitable for very specific gearboxes and applications. Redline website copy "Avoid use with pumps, coolers, and filters as unique medium and affinity for metal can cause clogging" I assume the emulsion can solidify or settle and block those up. Bad news, the 355 has a heat exchanger in the transmission oil line and a pump so you probably want to clean that lot out too.
