I had searched for hours in this forum and can't find anything. So I would like to ask shops/people which oil weights are use during new built engine break-in period? Thanks.

 

Picked mine up with 50 miles on the block, they used Castrol GTX 10w-30 conventional for the break in and tomorrow I am doing my first 3000 mile oil change and they told me to go to Mobil 1 0w-40 synthetic.

This was from GTM.

 

i ran rotellas diesel oil 15w 40

 

ran 5w-30 dino for break-in then went to 10w-40 syn.

 

10w40 Napa's best conventional for break in. 1500miles switch to Motul 300V 10/40 for winter , and 15/50 for summertime and warm climates.

That's what we use..opinions will vary.