Nissan Repair: Synthetic Oil, nissan sunny, conventional gear

Question
Hello Sir, I see a lot here about synthetic oil and the supposed wonders ot it.I know nothing about it and dont pretend to.However I was recently given advice from here tyo use synthtic oil in the gearboxes of 2 manual cars I have both which are a bit scratchy in the gearboxes.1996 rover 214 and 1992 nissan sunny. The motor factor seller said today that he only knows of half-synthetic oil.Is this the same? Then he told me that this oil would do more damage than good on such old cars?Is it abrasive or what? He recommended gear oil additive to help. Please give me your opinion on all of this as I am in a bit of a dilema over what I should do. Thanks for all your help...Michael

Answer
Michael,

I have had good luck with synthetic gear oils and with some additives.  For me, I love Mobil 1 brand synthetic but there are several others out there.  You can go to a parts store and check out what they have.  The half synthetics are not as good since you have less of the polyester components that make the fluid slippery.  But, it is better than conventional gear oil.