Time of first oil change after overhaul on Lycoming IO-360 engines

[Martin S.]

Evening gents,

Is there a consensus on when to perform the first oil change after an engine overhaul? I’ve heard recommendations ranging from 10 to 25 hours, but I haven’t been able to find any official guidance from Lycoming on this matter.

For context, the engine ran for 2 hours on the test stand, and the oil was drained afterward for shipping. So technically, the first oil change has already been completed.

Many thanks,

Martin

[EricJ]

Follow the break-in guidance from your overhauler.    If they don't have any, follow the Lycoming break-in guidance, which includes oil changes.

[jetdriven]

Generally, you change it after five hours hours and then you’re good for 50 but we will still do the second oil change at 25, the third oil change you can put AD oil in there with cam guard

[Justin Schmidt]

I did 15hrs...and found a crack in the case

[Ryan ORL]

The general guidance was usually that break-in is done when oil consumption stabilizes.  However long that is.

[good2eat]

Just went through this.  Changed at 5, will do again at the next 25.

[jetdriven]

On 3/4/2026 at 8:22 AM, Ryan ORL said:

The general guidance was usually that break-in is done when oil consumption stabilizes.  However long that is.

For all the engines we've hung lately, they never did consume oil. But after about 50 hours, the cylinder walls are pretty well broken in, and the protective varnish glaze starting to form. So I would take it to mean that the thing isn't broken into 50 hours and then you can put cam guard and AD oil in it. Continental says you can put AD oil in it for break in and I've seen that done for Lycoming's as well, so it probably doesn't matter. 

[Bartman]

After the second flight which was a total of about 4 hours I changed the mineral oil including oil filter and the dreaded filter screen. Temps were stable by the end of the first flight and if it used any in the first 4 hours, it was negligible.  Changed mineral oil after another 10 hours and then another 25.  That’s about 40hr on mineral oil and I’ve been on Phillips AD oil since then.

I add 7 at oil change and it stabilizes around 6 quarts on the dipstick as expected.   

[TheAv8r]

On 3/3/2026 at 4:10 PM, EricJ said:

Follow the break-in guidance from your overhauler.    If they don't have any, follow the Lycoming break-in guidance, which includes oil changes.

^ This is the right answer. Your engine warranty is tied to following their break-in instructions. 

On my IO-360, my break-in instructions from the engine shop were to change it at 10 hours, 35 hours, and 60 hours, then after the 60 hour change you could resume to normal oil change intervals. 

[Will.iam]

9 hours ago, Bartman said:

After the second flight which was a total of about 4 hours I changed the mineral oil including oil filter and the dreaded filter screen. Temps were stable by the end of the first flight and if it used any in the first 4 hours, it was negligible.  Changed mineral oil after another 10 hours and then another 25.  That’s about 40hr on mineral oil and I’ve been on Phillips AD oil since then.

I add 7 at oil change and it stabilizes around 6 quarts on the dipstick as expected.   

Is 6 qts after a few days to let the oil drain back down or right after you run it? I wonder where my qt goes since the oil filter is not holding a qt in fact it seems i can only fill up a 1/2 qt in the filter before it’s full. I get the oil is still clinging inside the engine but after 2 days you would think i would get that 1/2 qt back. If the theory is it takes longer than 2 days well i only drain my oil overnight so some of that old used oil would still be in those longer than a day spots so the total old plus new oil shouldn’t be 1/2 qt gone if you just idled the engine for 5mins checking for leaks after you were done. 

[Justin Schmidt]

1 hour ago, Will.iam said:

Is 6 qts after a few days to let the oil drain back down or right after you run it? I wonder where my qt goes since the oil filter is not holding a qt in fact it seems i can only fill up a 1/2 qt in the filter before it’s full. I get the oil is still clinging inside the engine but after 2 days you would think i would get that 1/2 qt back. If the theory is it takes longer than 2 days well i only drain my oil overnight so some of that old used oil would still be in those longer than a day spots so the total old plus new oil shouldn’t be 1/2 qt gone if you just idled the engine for 5mins checking for leaks after you were done. 

No need to over think it. I just go up for hr, come back drain, 5 min are so it takes for filter and other checks, put oil back in.

Oil is going to be coating everything, in galley, cooler, lines etc