synthetic oil? how soon to use in new motor

The main reason to use sythetic is to extend the oil changes to 6,000 or 8,000 miles. To keep you warranty you must change your oil at the recomended intervals, with Dodge and Ford (and I assume Chevy) they recommend every 6,000 unless its seeing severe duty then every 3,000 miles. When you read the details driving your car anywhere in North America is severe duty (climate etc..). To keep your internally lubed engine warranty you must change your oil every 3,000 miles even if you are using synthetic.

So far as warranty, Amsoil went to court many years ago and got that straight. The dealer has to back the warranty of the car and Amsoil backs the oil. If the oil fails Amsoil takes care of repair. If engine fails dealer takes care of repair. The engine would have to fail because of oil failure for Amsoil to pay. That isn't going to happen if you follow instructions. Dealer has no choice. Some years back there were some dealers telling folks they had to use a certain name brand and weight of oil. If they tell you that then they have to give you the oil at no charge. That was a court ruling also.

Now you can tell the dealer what you're about to do and he may or may not go along with you and argue. Or you can go ahead and change to synthetic oil and drive extended drains and never say a word and keep down a fuss. As long as you keep the proper oil level, change filters and oil at the proper time you have a warranty from Amsoil and the dealer.

Think about this. Have you ever heard of an engine failing because of oil? I haven't. It's because of the lack of oil.

I've used Amsoil since 1989. Never had a problem with it. I use it in two diesel tractors(my dealer knows about both of them), 3 trucks, a jeep and 1 car. They're from 1987-2005. Have driven as many as 16,000 miles on a change and average 14,000 per year on a nissan. Have engines with 6,000 miles to 258,000 miles and none get but one oil change per year with filter and a second filter change at 6 months.

Again as far as warranty that battle was fought many years ago and the auto suppliers lost. If the dealer argues, get him to call the top brass in his company and he'll get set straight. If he won't call, you can.

Many high end vehicles come with synthetic oil from the factory. Of the top of my head, some Cadillacs, Vettes, Porsches and VW diesels all come with synthetic.

Old belief was that a new engine wouldn't break in on synthetic, I guess that was put to rest long ago by the manufacturers