Z31Gold

I have a quick question about engine break-in. I am finishing up the engine rebuild process for my na2t project on my 85' 300zx. I had the block bored out, installed new cast pistons, rings, bearings, etc.. I have heard that running break-in oil is necessary thing. This being my first full engine rebuild on my own, I'm just wondering if this is something I should do, or not worry about. I plan to run a synthetic blend oil for now, if that makes any difference. Thanks.

ken99

Simple use a conventional oil for the first 3,000 to 5,000 miles. After that, use what ever you want.

PredatorZ

many manufacturers fill they're new engines with Mobile 1, so really use what ever oil you want, but I would do an initial oil changed withing the 1st 500 miles, cut open the oil filter and inspect it for metal shavings, most likely you will only find a small amount, but if you did find a lots of metal shavings, you could have a real serious problem. Engine builders(hi performance) will do it several times while testing an engine on the Dyno, pull a few hard runs and cut the filter open, if it looks OK... put it in the car, if not tear it down and find the issue. Frequent oil changes in the early stages of a new motor can significantly extend the life of the engine.

ken99

Using this analogy, would we recommend Z31Gold use 5W-20 viscosity oil? No, that would be silly. I would agree with this comment if Z31Golds VG30 had been manufacturered in 2014 to modern tolerances, but it wasn't. Yes, manufacturing techniques have advanced so far in 30 years, new engines require little or no break-in and have tolerance tight enough to use much thinner oils. In 1985, the original owners manual for the car called for a 1,000 mile break-in period with a specific set of criteria. Since some friction is needed during break-in, I wouldn't try to minimize the friction by using a full synthetic.

I strongly agree with this point. On all my new vehicles and rebuilt engines, I change the oil and filter in the first 1,000. Performing this task at 500 miles doesn't hurt a thing.

Z31Gold

Thanks for the quick replies. I'm still a little confused about which type of oil to run at first. You say I can run whatever oil I want, as long as I do an oil change within 1000 miles? Has anyone had experience with doing so on this motor without issues?

86ZxPROJECT

Honestly, I simply use Royal purple engine assembly lube when I rebuild the motor. Then I use Royal Purple conventional (weight depends on what the car needs to run...) And run the car for 500 gentle miles (don't redline, or stress motor with hard runs etc...) Inspect the oil filter (go ahead and cut it in half with a hacksaw... check for unusual amounts of metal shavings... if it looks good then continue on...) Then I change the oil, go another 500 miles. Then change oil and run like normal.

Z31Gold

Ok, sounds easy enough. I did use assembly lube during my build process, so I think I will just run a conventional 10W-30 for the first two oil changes at 500 mile intervals. Thanks for the replies!