Rant on Oil
Use Synthetic Engine Oil!
That said... We started using a 0W30 Esso Synthetic oil in all of our engines because it made them start so much easier in the winter. Then, Walmart stopped carrying it and the only way we could get it here was by the litre at the gas station which proved prohibitively expensive. Our Volkswagen engines now run 0W30 Motomaster Synthetic from Canadian Tire. It is a cheap synthetic that allows the engines to spin well in the winter. As of 2005 we switched oils again to Royal Purple synthetics due to an excellent cost deal arrangement. Giggles' engine has drunk that quite happily too.
We used to use Pennzoil GL-5 in the transaxles, but through our research into transmission oils for the UniMoG, we learned about the yellow metals issue with GL-5. We have since switched to Pennzoil GL-4. The second gear synchro in Giggles actually seems to have improved in operation since the switch.
Here are good web sites for oil comparisons and oil filter comparisons.