So, better to use water or seafoam for the intake?

 

Better is neither. I personally prefer sea-foam simply because its a petroleum product. If there is an advantage to using seafoam, it could be that it works faster(?) and does provide some lubrication . If you don't have the $7 to throw down on sea-foam, water is an excellent substitute. I'd use no more and not much less than a quart of water to do an induction service.

 

What do you mean by better is neither?

 

Meaning neither one is "better" than the other (at cleaning carbon buildup), its relative. Better is whatever you determine your more comfortable using. Better is water because its free. Better is seafoam because it may do the same job in less time. In the end, done properly, they'll accomplish the exact same thing.

 

k thanks

 

Back to the OP's question...

I will add that your new A4 should have had synthetic from day 1. I hope that it did, anyways... Sludge problems would be a concern, if it wasn't used.

And you shouldn't be using 5w30, you should be using 5w40 Castrol Syntec, 0w40 Mobil 1, or another Audi-approved oil. None of the approved ones are 5w30 that I know of.