i need u ppl's suggestion...through out,i have been using caltex havoline 10w-30..but during this summer ,i used caltex mobile oil 20w-50 ....as the winters r coming....i m planning to switch back to caltex havoline 10w-30...the car has done 127500 kms....do u thnk that i should go for it or use some other oil wich is in b/w these two in terms of viscosity....