low oil pressure
Just my opinion...but I think adding thicker oil to boost pressure would only be masking a more serious issue. Low oil pressure is an indication of an underlying issue. First, make sure your sending unit is functioning properly and then verify your gauge is reading correctly. If so, its time to open it up and check oil returns, pump pickup, oil pump...and then on to clearances. But don't ignore it. My buddy tried the thicker oil trick to boost pressure...it worked...until he made a pass at the track and it seems the thicker oil was unable to return to the pan fast enough at 7000 RPMs and "BANG". There are alot of details and steps involved to diagnosing your issue...but don't put a bandaid on it, please.
Just my opinion...no better then anyone else's