Rusting of fuel tanks is quite common with TVS Bikes. My Shogun's fuel tank was replaced FOUR times under warranty by TVS. TVS engineer had suggested me to put about 50 ml 2T oil for a full tank of petrol on a regular basis to avoid the rust. So, the last replacement did not suffer from the Rust malice for a long time. But, now the tank has rusted through and through since it is used sparingly. Guess the anti-rust coating should do the trick. Sad that TVS has still not found the solution for this problem.
-HARSHAVARDHAN