Michael wrote:



On the other hand, if you do make an entry, an ambitious fed can bust
you on it. For example, how many of you log that you performed the
change (gapped plugs, changed filter) in accordance with the Lycoming
(or Continental) service manual?

Not necessary in the US.



An owner is permitted to perform preventive maintenance (elementary
operations in Canada) but he is still required to perform it in a
manner acceptable to the administrator.

Yes.


That generally means in
accordance with the aircraft (or engine) service manual or other
publication.

Yes, but you don't have to write that in the logbook.


If you didn't log it, it didn't happen. So clearly, you
performed the preventive maintenance in a manner that might not have
been acceptable to the administrator. Busted.

No. Prove the oil change was done wrong.