On a well known VW expert website is the following statement: "We do not sell or use synthetic engine oil for the air-cooled VW as it rejects heat. The air cooled VW depends on the oil to soak up the heat from the head and carry it back to the oil cooler. With the synthetic oil the head temperature goes up and the oil temperature went down. I am doing some testing on a new development in the synthetic engine oil that is advertised to pick up heat from the oil and take it to the cooler without viscosity break down. I will let you know in the future if it lives up to its claims." I'd love to hear BITOGs experts opine on this.