Canola Oil

I bought a 2L Sunfoil Canola oil with BB date 25/06/2017 the other day, but when we used it to make mayonnaise it had a horrible flavour. Turns out the bad flavour was caused by the oil. We took out the other 2L we had in the pantry with BB date 13/05/2017, and this smelt and tasted perfectly fine. I understand that oil is a natural product and that it might differ from batch to batch but this really is inedible. i have both samples should you wish to collect it for analysis. Thank you for taking the time to read this.