I am not saying that people are wrong about the temperatures some places actually use but it does seem backwards. A friend who was a great lover of pomme frittes was adamant that they should be plunged in the higher temperature first to seal the outside and prevent excessive grease absorbtion.
I beg to differ with your friend the gourmet, Ned, but the whole point is to allow a little of the fat (gotta be lard) to soak into the spuds. The second, higher temperature, frying crisps them and prevents them from being overly greasy. That’s what gives them that special flavor.
Fix some for him sometime and he’ll love you forever. I guarantee it. 
Peace,
mangeorge
Shit!! I knew I should have previewed! Filets cook at 350. My bad!!
Perhaps something everyone is missing here is that McDonalds fries aren’t just flash-frozen before shipment. They are also sprayed…with sugar! A light coating of sugar and other junk is sprayed on the fries.
It’s been 6 years and I am quick to forget the nightmare that is McDonald’s management (which I did for, ugh, 3 years?). Why, o why would we bring it up again?!
Anyone who works there, read the ingredients on the side of the box. Its more than just potatos fellas.
One of the above responses states that sugar and a variety of other junk are put on the fries. This could not be more accurate.
While on a trip in Pennsylvania two years ago I went to eat in a McDonalds, and after I had payed for and received my meal, one of the employees behind the counter, dropped a batch of fries on the floor while attempting to scoop some fries into those odd shaped cardboard containers (why are they shaped like that anyway?) whereupon another employee mumbled “that’s okay.” and preceded to scoop the fries back into the rest of the batch under the lamp heater. Later, (I swear I’m not making this up) a kid was walking away from the “restaurant” with fries and said “These are good mommy,” whereupon I almost gagged.