just surprises me to why VW wouldnt just use 504 do oil Changes every 5k and have less repairs and a better reliability record vs 10k oil changes with 502 to save money?
Because they don't want their cars to be seen as requiring more frequent maintenance than all the other Euro makes.
There is no evidence that doing 10K oil changes with 502 results in any better or worse reliability than doing 5K oil changes with 504.
That, and they probably have deal with Castrol. So they are getting dirt cheap Castrol 5W40, doing 10K OCI, they look like any other Euro manufacturer, plus, they take $600 on deposit cleaning.
Now, if they start to use 504.00/507.00 that means using more expensive oil, which means increasing price of oil change, plus doing it every 5K. So average customer that has no any idea what is going on under the hood, will ask these questions:
1. VW is in the start more expensive then comparable Honda Accord (same equipment etc).
2. Honda Accord (or similar car) requires any 5W30 synthetic oil, meaning, if you go to 10 minut oil change place, they will change your oil, put Mobil1 5W30, refill your fluids etc, everything for some 59.99. In the meantime, if VW starts using 504.00/507.00 they will at least charge it 99.99, plus you have to do it every 5K, plus only in dealership (we are talking here about average Joe).
I have friends that drive VW, we start discussing cars, and I get out of conversation ASAP as soon as I realize that they bought car just because it looks nice, nothing else. If I start talking about all this, they would probably sell their car. They are happy, they think that is how things work, and I just leave them with that.
On other hand, people that hang out here are enthusiasts, and the way we maintain our cars, they can make 400K if you ask me.
So, while this discussion is useful I think it is more along the lines that we just like to do something under the hood, so we are trying to find excuse to experiment