Because that's what the dealerships and VW AU say to use. I thought I knew the manual fairly well and I haven't seen the bit you are referring to. Can you post it?
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This is my MY18 GTI manual but I've seen someone with a Polo show the same thing. Where fuel does not meet EN 228, 502 oil must be used according to the manual.
Attachment 50744
I can't explain it.
In my 2007 model it's simply "variable = 504. fixed = 502. 504 can be used on fixed interval" No mention of fuel quality.
I'd suggest you ask the VW AU tech heads. Or direct your question directly to Wolfsburg.
Hey guys. B9 RS5 owner here. Looking to do interim oil changes (6 monthly). Any reason why I wouldn't use 5w30 504 spec oil given temps in Melb won't be below 5c for the next 6-9 months?