I just turned 500 miles and changed the oil in my new 350 today (Valvoline 10W-30). I changed it after the first 30 minuites too. I was wondering how many miles till you could call it broken in? Im running moly rings so those may take a little longer, right? I am really curious because after only 500 miles the oil was perty dark, I was running a Pur One oil filter and the engine was assembled Very clean and was washed after I brought the block home from the machiene shop. I also noticed a little bit of blow back from the crank case. I have a fuel filter as a crank case breather filter and felt air blowing out of the crank case through it, not bad but I could still fill it. I guess this is from the rings not seating yet, and I hope it is normal. The PCV valve seems to be working but the gromet is hardned and Im going to replace it tommorow.
Thanks,
Mike

Good Guys Wear Bow-Ties
[img]/wwwthreads_images/icons/wink.gif[/img]

<font face="Comic Sans MS">Perhaps 5,000-7,000 more miles and it'll be broken in... [img]/wwwthreads_images/icons/crazy.gif[/img] Since everything isn't worn in yet, you should be able to expect a bit of blow by and even oil consumption... Also dark oil is another normal thing. It's all those tiny metal particles wearing away. Regardless of how shiny/smooth a surface may look, on a microscopic level it's still really rough. [img]/wwwthreads_images/icons/crazy.gif[/img] Nothing to worry about. </font>

Tim "Sandman"

ORC Land Use columnist:
My May Column