Bluebee-I drilled only 2 layers at a time. With hindsight, I probably could have drilled through all 4 layers at once. I was concerned with retaining the strength of the tube so wanted to stagger the holes. I think more holes is better than less. BTW I used a 3/16 drill bit.
I agree with you absolutely about BMW ripping us off with their "new" dipstick tube. I can't fathom why they would build a double tube dipstick and charge in the $40-$50 range and then build a simpler, one tube dipstick and charge 3 times as much.
You can keep your double walled dipstick from getting clogged by driving your car for longer periods once in a while. It takes a long time for all the engine oil to get up to full temp-maybe 15-20 minutes. So a 1/2 hour run would do that and then the dipstick would be in a nice hot bath which would cook the water out of the sludge and let the oil return to the sump as oil.
Jason-there are pics in post # 28 above. The drilling was easy-took about 1/2 hour from beginning to end. Also I have finally understand exactly what your mechanic did and why he had to weld up the outside hole-he drilled above where the dippstick goes into the sump, right opposite where the CVV drain tube joins the dipstick-right? I guess I may have to make more mods in the future.
Last edited by johnstern; 06-08-2012 at 12:41 PM.