boss if you have used pso gear oil its not for santro its labelled 140w
santro requires less thick oil around 70 - 90w
try out zic wich is 70- 80w i think (u can confirm these values from user manual )
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but if oil is of proper thickness then it might be issue with pressing of clutch ..........
you have to press clutch till it touches the floor of car ............
check free play of clutch as mentioned in user manual ......
if still not issue with clutch then claim warranty of gear box as there might be some serious issue with it ......
ur car is in warranty till 50k or 2 years which ever comes earlier ....