Regarding Oil they said Toyota recomanded genuine engine oil with proper grade(i think they mean multigrade).
I am completed with 3rd service and vehicle is returning 10+FE on highway and 8+FE in city with AC on.
Regarding Battery after my Exide battery gave up I switched on to TATA Battery with 15 months warranty. I feel Petrol Innova battery would last within 3 years because battery specification is not enough for this monstar
I suggest 225/60 R15 Michellin MXV8 tyre for Innova If comfort level is needed and G3 potenza is for performance and If you are on budget and travel too much in bad road buy bridgestone tyres. Max. size for Innova in ideal condition is 225/60 R15 if you ask me
Regards,
Ravi.