block honing process for cylinder walls creates horizontal "grooves" this is necessary to hold
oil. Theory is
synthetic is to slippery and instead of the cylinder walls wearing in / taking the peaks off the grooves the
synthetic is to slippery to wear in and it rolls/smears the peaks over and the rings never seat. I would give it 10k miles, that being said with all today advances in engine manufacturing I am sure the bit OEM have overcome this issue.