NO TRUE !
Any oil that does not contain extra lubrications are acceptable for brake in.
Remember all oil are mineral oils, except the synthetic blends.
Some of us follow manufacturer recommendations Tom.
Continental - IV. BREAK-IN PROCEDURES
We recommend these procedures to break-in a new, overhauled, or repaired engine:
NOTE: The following break-in procedures apply for through-hardened steel and Nickel+CarbideTM cylinder bores.
NOTE: Use 50-weight, aviation grade mineral oil for engine break-in.
Lycoming - There are two basic types of FAA-approved aviation oils used in general aviation aircraft piston engines.
1. Straight mineral
2. Ashless dispersant (AD)
Many Lycoming engines use straight mineral oil for “break-in” purposes with a new, rebuilt or overhauled engine. The operators should then switch to AD oil after “break-in” has been accomplished. In those engines that use straight mineral oil beyond the normal break-in period (25 to 50 hours), a later switch to AD oil should be done with caution as loosened sludge deposits may clog oil passages. Oil screens must be checked after each flight until clots of sludge no longer appear.
Those Lycoming engines that are to be broken in with AD oil include all turbocharged models, the O-320-H and the O/LO-360-E.