Ok, new conundrum for the Family to crack: DOT 4 low viscosity brake fluid.
The relevant quote from the BMW TIS regarding approved brake fluid is this:
All vehicles with DSC without a charge pump must be filled with the new DOT 4 low viscosity brake fluid.
So the question is, does our DSC system have a precharge pump? The bit of searching I've done leads me to believe we do not (though the E46 M3, and E39s, E65s, etc. appear to).
If I'm right, then the DOT 4 LV fluid options I've thus been able to find include:
- BMW P/Ns in the pic above: I've found 83 13 0 139 896, the 500-mL bottle, available from most of our favorite online parts shops (ECS, TheBMWPartStore.com, etc.). Note that this is NOT the same as the "normal" 12-oz bottle of BMW brake fluid (P/N 81 22 0 142 156).
- Pentosin DOT 4 LV: fairly widely available (Amazon, AutohauzAZ, etc.)
Another possibility is ATE's SL.6, labeled as a "DOT 4 (Class 6)" fluid. Pentosin's spec sheet for their DOT 4 LV lists "ISO 4925 Class 6" as a specification it meets, so perhaps Class 6 fluids are LV? (Or that could be a square-rectangle thing . . . )
So whaddya think? I'll probably "play it safe" & get a couple bottles of the BMW LV fluid.