Eh, I don't think it will be a problem. It might help the seals soften and seal better, but if you don't mind paying a little extra for the blend, I say leave it. You might get some leaks due to going to the blend, but if you don't mind that, I'm sure it'll be just fine.
"...What IS true: We anticipated that this would happen - we are never finished - and yes, Ford DOES deserve to win now and then. To think that GM can come out with a car to make ford throw in the towel is simply foolhardy..." - fbodfather