[Crosseye_Jack]

If you make your warranty terms perfectly clear you will be fine, there is nothing stopping you from going above and beyond the terms at your own discretion.

You would have issues if your warranty said "we will cover you for (random thing plucked out of the air) battery replacements for the first 2 years" but would only replace batteries for your whales as you are in breach of contract with your non-whales.

You have to stick to what you agreed to with your customer in your warranty terms, but you are free to go beyond those terms at your own cost as you wish as customers were aware of your terms at time of purchase.