Using good quality oil will give your engine the best chance for a long and healthy life. However, not all oils are the same, not all high quality oils are right for our beloved air-cooled unit, and there is a lot of myth regarding which is the correct type to use. So we’d like to try and set the record straight.
In the early days VW originally specified straight mono-grade oil for the Beetle engine. Remember, this was a long time ago, and most manufacturers specified mono-grade oils because multi-grade oils were in their infancy, and frankly they weren’t that good.
The grade of oil was specified as straight SAE 30 for most general driving conditions, with SAE 20 specified for winter or colder climates, and SAE 40 specified for high summer or warmer climates.
The introduction of new oil standards in the 1970s brought the advent of better quality multi-grade oils, with the result that in 1975 VW specified multi-grade oils for all new air-cooled vehicles, and recommended that older vehicles also follow the new specifications. The recommendation was for oils of SAE15W-40 or SAE20W-50 or similar for European climates. All air-cooled engines since this time, up to the latest Brazilian/Mexican engines, specify a multi-grade oil.
We therefore follow VW specifications and recommend a good quality multi-grade mineral oil such as the Quantum SAE15W-40, or similar quality brand. There are those who claim that multi-grade oil breaks down at the high oil temperatures that the air-cooled unit runs at. We disagree – if your engine is operating at temperatures that breaks down the oil, then your engine is running far too hot! You need to reduce the oil temperature, not use lower specification oil.
Synthetic oils typically have quite different heat transfer characteristics to mineral oils. On modern water-cooled units this is not a problem, but on the air-cooled unit where a significant part of the overall engine cooling comes through oil cooling, the use of synthetic oils can cause problems. As the amount of heat dissipated by the oil is reduced, the engine runs hotter.
Therefore, for every day use, we recommend mineral oils, not synthetics.