I just put the manufacturer specified oil in my engines and change it at sensible intervals.
Q5 VW spec synthetic 5w-40 they say change at 16,000 I change at 8000
Fit This MkII fit specifies a Honda 0w-20 which like all (AFAIK) 0w oils is at least a partial synthetic. Change interval on maintenance minder is between 11 and
12000 or once a year...we do it once a year as the car has only just got to 12,000 after 22 months.
Previous. M-B B250 maintenance minder said every 12,000 or once a year with an MB spec 5w-40 or 0w-40 synthetic. Sold just as it got to 12,000.
Mk5 GTI, A4 1.8T both said a VW spec synthetic and change at 16,000 Both changed at 8000.
BMW 330Xi 5w-30 or 5w-40 synthetic at about 22,000 to 25,000 kms Changed every 8000
MkI Fit 5w-20 dino oil, maintenance minder on that car went off at 8000 or once a year. Only in one year did we ( she actually!) do enough kms to change
before the year was up.
The only one of the above which used any oil was the BMW which used perhaps 1/4 litre in 8000 kms and stopped using oil at around 20,000 kms or so.
So from this I draw the conclusion that the FGC engine manufacturers see an advantage in synthetic oil for normal road cars in this climate...why would one argue? Let alone any potential warranty issues.