Audi recommends a 10,000 mile interval using conventional oil. I decided to run Mobil 1 5W30 (couldn't get 0W40 at the time). Here is the report from Blackstone Labs.

http://surf.to/cnewton/gifs/oil-change-report-audi-a4.jpg

What do you think?? I now Castrol Syntec 0W30 (VW approved ACAE B3, etc) in the crankcase for the next interval.

Iron and copper wear is important, except if your engine is running the first miles.
Most important is 30 ppm of lead. Are you sure yuo are using unleaded gasoline? This thing colub be a very important point to be checked.

In industrial lubrication the rule of thumb is that you can go 1 grade of oil higher in viscosity and be okay, but we don't usually recommend going lower. It looks like you substituted a 30 where Audi specified a 40 grade. Is that standard in automotive lubrication?

Actually in the USA audi recommends 5w-30.

In europe they use 5w-40.

2003 Audi A4 1.8TQ
Amsoil 0W-30 Synthetic
Amsoil Full Flow synthetic/cellulose filter.

Yes, I have only used unleaded gasoline (don't even think leaded is available in US).

The manufacturer calls for 0W30, but will accept 5W30, 5W40, or 5W50.

I am running Castol Syntec (0W30 made in Germany) right now, will get another sample at 40,000 miles (will have 6,500 on the sample).

Curt

This is not scientific but I've noticed that when changing brands of oil. The first run of a new oil sometimes reacts with the leftovers from the old oil. Causing the TBN to drop faster on the first sample of new oil than the second run sample. Thisd I've seen in analysis posted elseware and in my own oil analysis.

I noticed this in my own VW TDI when I was changing from VW factory fill 5w-30 to Schaeffer's 15w-40. The TBN dropped much slower on the second round of Schaeffer's as compared to the first round.

First analysis 10k on vehicle 5k on the Schaeffer's TBN 6. Second analysis 20k on vehicle 10k on the Schaeffer's TBN 9.

Correct me if im wrong, but doesnt the TBN drop faster on the factory fill becuase of the extra friction during break-in of the motor??

2003 Audi A4 1.8TQ
Amsoil 0W-30 Synthetic
Amsoil Full Flow synthetic/cellulose filter.

I'm curious, Curt, why you would choose to take the next sample at 6,500 when the report suggested to do the next sample at 5,000.