Can anyone that has installed a ZZ4 tell me what oil weight / viscosity I should put in for the break in miles?

I don't buy the 50 weight oil recommendation.  I have a new GM 350HO in one of my cars and the shop that installed it put in 10W30 dino, not synthetic oil.  The manual for my engine doesn't give a recommended weight motor oil, but does say it should carry 40 psi oil pressure at 2000 rpm's...I assume that means at normal operation temperature, but doesn't specify. 

You'll get some different recommendations when to change your break-in oil...some will say change it at 100 miles, some will say at 1000 miles or even different.  My engine is about to hit 500 miles and I plan on changing it.

The shop that installed my engine told me that if I want to use synthetic oil to wait until I have 5000 miles on it before doing so.  Others may say different or agree, but I'll likely stick with dino oil with regular oil changes.

 Id say 5---30,,and id change the oil and filter at 750 to 1000 miles,,run the engine up and down the scale,, low rpm and a few shots at high rpm,,id run it a few times without a load and with a load also,,in gear and outa gear)  after the initial oil change, id change it again after another 1000 miles, after that,, just normal changes,,id also get a magnetic oil plug and look for metal shavings,, good indicator of any bad bearings ect,,rd

You're gonna be changing the oil out fairly quickly anyway, but 50wt???? NOT!
I'd recommend using Delo400(diesel oil), or the Rotella Diesel oil for engine break-in. These oils have all the good stuff that a fresh engine needs to keep from gaulding itself to death. The new oils on the market don't have any of the stuff, unless you buy the additives that are out now specifically for this purpose.

my .002 Adams' Apple2008-03-30 19:41:04

Carl, Ten152008-03-30 19:30:47

Thanks to all that replied! I will go with the recommendations for a non-synthic 5 or 10W-30 weight oil and change out oil and filter frequently for first 1000 miles. The recomendation I just got from the GM Engine Depot where I bought the engine was for 10W-30 non-synthic oil as well.

Valvoline 20-50 racing oil has a high zinc content.................Google....."engine oil bible" and you can get overwhelmed with oil information.

I broke my zz4 in with castrol 10-30, changed it couple times before 1000 miles and still use it today.  That was 5 years ago?... maybe 6,  and i still have 75 psi at the top of the block next to the distributor untill the block gets some miles on it to warm up. 

Don't use synthetic whatever you do...

AS WAS MENTIONED.............YOU CANNOT USE SYTHETIC OIL in your engine until the piston rings have set. This wouldn't be until at least 1000 miles. Make certain to use the GM break-in additive Part #1052367. This has all the extra mineral additives that you will need. Edelbrock uses ZZ4 engines. They recommend 5-30W(mineral oil) for the 1000 mile break-in. I would, because I'm anal, change the oil at 100 miles or sooner if it's been running a lot to get set up. Oil is cheap insurance. You can't really go wrong by over changing it. But again, get the additive from any dealer. It's not very expensive about $5.00. Use the additive until 1,000 miles, meaning if you change the oil before 1,000, re-install the additive again. After 1,000 miles Edelbrock recommends going to 10-30W oil. One more thing recommended is to remove the distributor, allowing access to the oil pump drive. You then use a adaptor with a drill motor to drive oil throughout the engine...........without moving any of the internal components. Once this is done, you drop the distributor back in and can fire up the engine. Make sure to index the rotor properly. Good Luck, Larry   corvette440hp2008-03-31 11:11:11