When I installed the new tubes I just used engine oil.  It went fairly well until I had one rubber stick and leak when runup.  I called the company and the owner immediately knew that I had used engine oil to lube the rubber gaskets near the crankcase.  He talked me through getting it to seal.  In talking with him there was a specific lube recommended that he said would not stick and would flow into the crankcase hole and seal.  “Shoulda, coulda, woulda.