<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by f5fstop:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by PhilD:
You can put it in straight away, no need to wait. Mercedes, BMW, Aston, Corvettes all come with Syn from day 1.

There is absolutely no reason to wait with today's modern engines. But you can if you want. </div></BLOCKQUOTE>

That is true, you can run it from day one, so long as it meets GM specification GM6094M, and every synthetic I have ever seen meets GM spec GM4718M, which is actually a higher specification than 6094.
However, on another note, do you require synthetic? Modern oils meeting the GM spec 6904 are extremely reliable, with excellent additives. </div></BLOCKQUOTE>

Porsche also fills the crankcase with Mobil 1 snthetic from day 1. But many Porshces are used as weekend toys (low annual mileage) so the oil change intervals of 15K miles or once per year make sense since they all carry over 9 quarts.

Hummer owners can ponder the use of synthetic oil, but few will enjoy any noticable benefit during the time that they actually own the vehicle.

S.