Is there any information out there on the recomended equipment (lower
cylinder cowling covers, oil cooler cover, lower cowling cover, etc) to
install on a Continental 145 equipped 1967 172H when flying in temperatures
below -20 degrees Celcius? I currently have the lower cowling around the
wheel strut closed off and the oil cooler blocked off, which has helped
maintain oil temp. Is this enough? Has Cessna issued any bulletins?

Thank you for any help!

You need a whistle slot in the crank case breather tube... Your A&P
knows what this is...
Continue to increase the amount of airflow being blocked until the oil
temps stay in the normal range at cruise power.. Keep an eye on head
temperatures so they don't get too high...

denny