What’s the best way to indicate in a feed that a product is on sale for a limited time?
- Include “SALE” in the title of the item
- Upload the same item twice, once with a lower price
- Use the ‘sale price’ attribute
- Update the description of that specific item
Sale price attribute should be used in your product feed if your product is on sale. Submit the sale_price in addition to the price attribute with the non-sale price.
Read more here: https://support.google.com/adwords/answer/188494?hl=en