Thread: Synthetic oil in newly built motor

My motor was recently rebuilt and I was wondering what oil to use at which stage.

For startup I was thinking regular Shell Helix 20w50
Then for the first oil change Shell Semi-synthetic 15w50

At which point can I switch to full synthetic (I'll be using Mobil 1 0w40)

The cylinder bores were honed, new piston rings, new ACL race bearings.

sounds about right, ive always heard and been told to use conventional oil for the first 500-1000 miles.

It is not practical to use synthetic when breaking in an engine because of metal particles from the break in period necessitating that you change the oil at 1000 miles. Sometimes even less. It is purely a cost issue. Think of all the factory cars that roll out with synthetic oil right off the lot. Corvette, STI, EVO, MS3, etc. The synthetic break in is a myth. No harm could come of it.

It just doesn't make any sense to put $50 worth of oil in your engine when you are changing it out in 500-1000 miles.

I would stick to your current plan Doc, it sounds like a good one.

Doc, stick with what you want to do. I had my .020 overbore lowport DE broken in with 5w30 dino oil for the 1st 5-1500 miles then did Valvoline Durablend 5w30 for the 3K after. Switched to Mobile1 and went 30K without a hitch until I VE'd the car. Not to say the newer cars have the up to date piston rings that break in easily even with synthetic oil as recommended by the manufacturer but I'm old school. I believe in what has worked for me so take my experience with a grain of salt. Only thing I would suggest is to go lighter on your oil weights to ease break-in. Maybe go 10w40 for your dino oil. Just a thought.

He's in South Africa where it gets super hot. 20-w50 and 15w-50 is pretty standard on the shelves there. 5w-30 is not. I'd break in real quick with regular oil for the cost then switch to synthetic. When I was down there I preferred the Castrol oils personally.

This guy has some ideas on break-in;

http://www.mototuneusa.com/break_in_secrets.htm

make sure you have a magnetic drain plug