ZZ-4 motor is filled with break in oil at GMP and pre-run. Check your dip stick to make sure. Ran break in oil 200 miles, changed to 10-30 Castrol for 1000 miles and use Castrol Sen-Tec ever since.

The guy that got my 270hp crate said to change it at 500, use 10W30 and run it at 1800 for the first 15 min after startup.  Then, for the next 500 miles, go thru the ranges and try not to do a long (30 min or more) stint at any given rpm. 

He and the engine guy he has working at his shop told me not to be afraid to get on it.  Then, after I had about 200mi on her, they asked if I had opened her up and I said no.  After calling me various and sundry feline names, they asked what I was afraid of.  Reminding me that I had a 3yr 100K mile replacement warranty on the thing, they said it would be better to blow it now than later.

They then quantified it as get into the barrels, but not hard on take-off or up a steep incline heavy load, but get into the back 2.

Man, this thing has so much more power than anything I have had in her to date.  Just breaking it in (430 miles tonight) I have found that it will make the tranny slip if you get on it for passing gear around 2 - 2500 rpm.

Can't wait for a present from Joel.  Too bad it probably won't make it in before Hot Springs.

Anyway, I guess I screwed up because I used Castrol Syntec for the first oil, as nothing was said about non-synth use and when I asked about the Rotella like I did the last (pos) engine, they said that isn't what GM vehicles have on the lot, so why use it in a GM crate. 

It sounds like I should be switching away from Synth, any more input from you guys on whether to use it or not?  Reasons? 

I also run the Fram racing filter and plan to stay with that.

The primary reason for not using synthetic oil for break-in is that the molecules are so small, it makes it difficult for engine rings to seat and to properly condition (or season) the cylinder walls.  Dino oil does this better in most cases. 

Many modern engines, such as the LS series aluminum engines, come with a factory fill of synthetic oil, but they are often broken in when assembled, and the tolerances are so close due to modern casting and assembly techniques they can get away with it.  The small block crate engines are still old technology in comparison, plus GM and other companies have no control over what they're being installed in, what induction systems and other parts are being installed with them.

That doesn't even get us into the subject of ZDDP for cam and lifter break-in, but the ZZ4 has roller rockers so it's not an issue.

So, have I terminally screwed this one up?  Can I change it out (by the time I get to 71Sharks shop, it will be 500 miles) or should I stay with what I started out with?

Since I started w/10W30 synth, should I change to 10W30 and go with non-synth?

I'm not too concerned with the guarantee and all however, I don't want to change another engine.

I'm not up to being set aflame again.

I'd go with Joel. I used Rotella, changed it at 300 miles than 1,000 miles.  I now use straight 40 weight, as I was experiencing blow by with the multi blends.  Get the magnetic plug and check for shavings.

I, too, agree with Joel.  Many of the people who give advice learned before the oil companies removed the good stuff from the oil.  Diesel quality oils still have those additives, which are especially critical during cam break-in.  Some people who have big blocks and lots of valve spring pressure use Rotella all the time.

Larry