I recall on the test...(you might want to confirm this) the oil for R12 is a type of light mineral oil. The PAG and ester oils are more hygroscopic (pick up water vapor) and could cause trouble. You don't need the certification to get the R12 oil, unlike the refrigerant.

Short answer - use R12 oil with R12 refrigerant, ester with R134a. The longer you vacuum pump the system before charging, the better.

__________________
1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!