What oil to use

I just replaced all for cylinders on my 0360
What is the best oil to break the cylinder in
Thanks you
Danny carley
15vr

lot's of threads on the subject. general view, including my engine manufacturer, is to use straight mineral oil like aeroshell 100 without any additives for up to 50 hours.

Follow the recommendations of the cylinder manufacturer.

Lycoming Engines publishes a lot on the subject. I like using Phillips 20W-50M and it is listed on Lycoming Engines Service Instruction 1014N Lubricating Oil Recommendations July 29, 2020.

More Lycoming links:
https://www.lycoming.com/content/hard-facts-about-engine-break
https://www.lycoming.com/content/oil-and-your-engine
https://www.lycoming.com/sites/default/files/Lycoming%20Reciprocating%20engine%20Break-In%20and%20Oil%20Consumption.pdf
https://www.lycoming.com/sites/default/files/Pre-Oiling%20Engine%20Prior%20to%20Initial%20Start.pdf

Check out AOPA's ask the A&Ps monthly podcast series. It seems to me that about 1/4 of the questions are about new engine or new cylinder break in.

Consensus is DO NOT use synthetic oil. Do NOT use anything with antiscuff or antiwear additives. Run the engine hard until you notice a sharp drop in temps - might only be a couple of hours if you do it right. And change the oil early. 10 hours max.

I took notes someplace with specific temp numbers for Continental and Lycoming temperatures before and after the rings have seated and the engine is broken in, but the podcast is very detailed and very specific on break in procedures.

I watched a couple Mike Busch webinars on engine oil... this is what he says:

• Break-in oil for aircraft should have:
  • Lower film strength (no synthetics).
  • No chemicals that promote boundary lubrication (therefore no Aeroshell W80 Plus, W100 Plus, Phillips Victory oil, or Camguard additive).
  • Good break-in oils are Aeroshell W100, Phillips X/C 20W50.

My full notes from those webinars go beyond the break-in oil question but are here.
.
.