engine breakin
 

ok i was wondering how long would i need to break in a new gm 350 engine. what oil should i run for initial break in? Should i run a synthetic with break in additive. and then switch back to regular oil or should i run synthetic for 40,000 miles then go back to what i was using which was valvoline max life. just curious because i need to start gathering parts and oils n such because i got a loan from my moms bank (i have no credit) and they had the check printed out before i even completed the app. and my bank took 4 days to tell me no. wierd huh....

i ran mine 500 miles below 45 or 50 mph. i dont remember exactly but i changed the oil a couple times in the first 3000 miles or so... i used regular oil. have been told not to use synthetic on break in. and to not switch back and forth.

Run conventional for the break in then if you want to use synthetic you can.

I broke mine in like all the other motors. Non-detergent oil and 1500 rpms for 15 minutes. Then drove it for 600 miles and changed the oil.

I broke mine in like I was going to drive it. Not raggin on it but I did get on it from time to time. Yes Full throttle. Have done that with every new car I have owned ...same goes for this one. Never had a failure or problem. And....all my cars stock to stock run better than others just like them. :)
I did use a cheaper oil for the first 500 miles then switched to synthetic

I have broken all mine in with no failures and once broken in, I have driven it like I planned to drive it...... I drag raced the 454 THE day I broke it in.

see...Im not the only one who does this!! haha
Hell, Im not about waiting a month or so to see how my new motor runs!! lol
I WANT TO KNOW NOW!! haha

I am with Chris and Dave...break em in like you are gonna drive them. I have only had to break in one engine...the sucker never let me down and never missed a beat...not to mention...the damn thing didn't even lose any oil whatsoever!! I wish I could have kept that small block...but I sold it to finance the big block. :(

-Jeff

I babied mine around for a little, but if you think about it, look at all the performance engine builders. They put them together, although put together rather nicely, bolt them to a dyno, do the initial breakin, change the oil and filter, and then hammer the hell out of them to see what they will do. If they are going to blow, they want to know about it then.

This reminds me of the guy I used to help with his dirt track car. He had a 350 built by the pros. He goes to pick it up and they had it on a dyno. They had done the initial breakin before he got there. Now it was time for the dyno pulls. They proceed to rev that thing to 7500-8000 grand. Brand new engine. We are all waiting for it to blow all to hell, but the engine builder said, if it blows, so what. I'll build you another one. :D

That is my outlook on it, If something is weak...break it right away while its under warranty. :) There are plenty of conflicting opinions on it but some do belive the ONLY way to seat the rings is by getting on it immediately.

I just broke mine in Non-detergent oil and 2000 rpms for 20 minutes and changed the oil/filter after break in.