I've read varying recommendations on changing oil after breaking in a new engine. Immediately after the break-in, after 50 miles drive time and as much as 500 miles. Just curious how people here go about it.

You might Youtube this Q & read what pops up, some interesting info

Typically, if I build a new motor requiring "break in" (new cam) we will do the normal 2,000 rpm once fired up until the motor gets to 190-200 degrees. We will typically try and do a test n tune at the track and make a few passes and if everything goes well, change the oil before the next outing. I have had one engine dyno'd. Mainly because it was my wife's Ford 351W and I had a very knowledgeable engine guy build it since I'm not up with all the tricks and what not to keep a ford engine together. We broke the cam in on the dyno and made 6 dyno pulls. Did a test n tune and than changed the oil after that outing as well. Our engines are fairly basic pump gas with flat tappet cams making 5-550hp, so nothing over the top and very mild compared to most other racers setups.

Break in oil is exactly what it says - break in the engine then change it. Break in oil does not have the detergent levels of a standard race oil . It was originally designed to break in the motor on the dyno and be changed out. If you follow NASCAR engine builders - they run the engine in break in cycles on the dyno then drop the oil and replace with oil that they intend to run for actual dyno pulls. Personally I would not run a break in oil more than a couple of passes if you did not dyno the motor.

I have a test stand to break in new builds. After the break in procedure is done (flat tappets), I'll let the engine run long enough to go through a few heat cycles. Then I change the oil.

I do the same as Chip.

Only exception is...or was....when the super thick gray moly paste was used (which almost nobody does anymore as that was much more a '70s and '80s thing....but some
folks may be heavily influenced by old publications where it was mentioned).

If and when that stuff is used, then it is a good idea to change the filter ASAP after run in, because it was known to sometimes plug up oil filters and sometimes
traces of it could be found in the lifter valley years after the initial build.

I did use it in my first 440 around 1988.
A year or two later I tore the top end off to make some changes, and there was some of the gray paste still in it.

After that I stopped using it inside the engine and relegated the moly paste to other things....

This is what I have come down to doing. Bradd Penn Break-in oil with a Jomar 100% No Bypass oil filter seems to be the best combination for initial ring seating. After the engine is run in and fine tuned on the dyno, swap out the break in oil and filter, inspect filter and then fill with high quality oil and a fresh Jomar filter.

We usually make a few pulls after initial warm up on the break in oil. As for HP have found very little between break in oil and standard engine oil. Talking 40wt break in VS 5w30. Just got off the dyno with two engines. One made no more power on regular oil than the break in oil, this was on my 1120hp Predator. The other engine my 600-13 we never swapped to regualr oil from the break in oil. The next owner can do that.

I use Valvoline 5x20 wt. as my break in oil on street only builds, I will change it and the oil filter on flat tappet cam motors after breaking in the cam and cut the oil filter apart to inspect what was trap in it to make sure the cam is not losing a lobe or two
On roller cam motors it depends on what the motor will be used for, street only gets the same Valvoline 5W20WT. oil street and strip motors and race only motors get Valvoline VR1 10x30 wt. oil
No synthetics oils for me yet Maybe soon
The main reason for me not using any brand or weight synthetic is they will leak when regular petroleum base oils do

FWIW I use BR40

You would be surprised what we use in the 980-1000" nos motors. 0/10 5/10

We use straight zero weight in the heads up car...Some power there