oils aint oils
I've got some info from oil suppliers and oils seemed to have improved a lot over the years.
Still need to change the oil at the specified interval however. Good to see that CASA eventually (some time ago) allowed tolerances on that interval. Before that you'd get a slap on the wrist for going a fraction over the time between recommended oil changes.
There doesn't seem to be the same interest in following the book on grade of oil. Flight manuals of most aeroplanes that I fly have the standard Lycoming statement:
"The following grades should be used for the specific temperatures." with a table listing "average temperature" and appropriate grade of oil, for example:
"Above 60 deg F" SAE 50
"30 deg to 90 deg F" SAE 40
"0 deg to 70 deg F" SAE 30
Melbourne in summer, I'd accept an average temp above 60 deg F but not winter. Melbourne in summer would also fit into 30-90 deg average temp.
Melbourne in winter definitely doesn't have an average temp above 60 deg F - that's not the average max temp - that's average throughout the day. So, why is it so difficult to get hold of SAE 40 oil down here? Why does everyone use SAE 50 regardless?