what cooking oil can come good with french fries?

You can't use any seed or bean oil. They are bad trans fats. No vegetable oil either. Olive oil has a low heat point so that will become carcinogenic if you heat it to deep frying point.

The best oil for frying is actually dripping. It's a saturated fat, but that's actually what makes it good.

Have a read of: http://www.marksdailyapple.com/saturated-fat-healthy/

Saturated fats are being proven to be good for you. They raise your good HDL cholesterol and are actually heart healthy.

Well i know that olive oil is healthy but idk if it will change the taste/look of the french fries. My grandma uses original vegetable oil but i don't think thats healthy.