fellow vanagon types 
My experience with oil over the last 30 plus years has been a slippery one  ( pun intended ) 
I have found that synthetics while they are in fact better lubricants are less likely to absorb heat although the one blended oil I tested castrol syntec did not have this problem. 
    The air-cooled engine is very different than the water-cooled engine due to the dramatic difference in operating temperatures. The water cooled very quickly comes up to temp  and stays in a very narrow range while the air cooled engine head and oil temps can vary by hundreds of degrees depending on ambient air temp, load and the amount time driven. 
    I have tested air cooled engines with digital real time instruments. I could tell if the driver had his foot on or off the gas pedal by the head temp gauge that's how good the information was. That I have learned from that was that the head temps in the air-cooled engines depended on the ability of the oil to absorb the head from the heads. When the non synthetic oils became saturated with heat and that happens at  225F the head temps rapidly climbed and the oil slowly increase in temperature. I also found that the air cooled engine accumulated heat over time. The best way to describe this is to say that when I took the engine on a 12 mile climb up a mountain after driving down a highway for an hour the engine went into thermal overload before the top of the climb I define thermal overload as oil temps in excess of 230F and head temps over 400F I have then taken the same engine and let it cool down after driving it for an hour on the highway and then drive it up the same mountain on the same 12 miles it did not get anywhere near as hot at the top of the hill. The gauges I was using can not be compared with the VDO gauge reading you would buy. The VDO gauges would be yesterdays news the event is over before the VDO would tell you how hot the oil or heads really got.
 The cooler running oil temps reported in the trends article I am sure did not report on the hotter head temps. 
People that use expensive oils tend not to change it as often and that is not a good thing in the air-cooled engine because they more than other engines can accumulate gas in the crankcase
This happens when not driven enough to fully warm up the oil and burn off the fuel and that becomes more of a problem in cooler climates
I think that the synthetics are not a problem in the vanagon WBX engines if they have been broken    

fast and dirty
going faster miles an hour  
I remain Boston Bob
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