After you try monarch's search, then do a search on "synthetic" and read all the endless posts of people that switched with high mileage and nothing happened. If an engine had regular oil changes throughout its lifespan then chances are it was/is well maintained, the internals are clean with very little build up.
Now, as always, here is the warning. If this becomes a rehash of the age old "oil debate" that we all hate to spend time reading but love to post in, it will be shut down. There are currently too many oil debates and threads throughout our database, so please, if you want to ask "which is better, dino or synthetic?", then search for it. We will not maintain oil debate threads unless someone has posted totally new information.
I understand some of you are new, but this discussion opens many heated posts and creates tension between members. Until new information arises, this oil debate horse is beaten and dead.
steviej
LOC Management.