Fixing the siphon jet so you can use the bottom 1/4 of a tank is not difficult.

You say the transmission slips when cold it's possible it just seems like it. It will stay in first gear for much higher than normal when cold I think it does that on purpose to warm the transmission. When you preheat the motor I think the transmission will get preheating from the input side of the torque converter spinning. Or perhaps the transmission cooler tstat opens when the coolant temp gets hot enough than that warms vs. cools the trans fluid.

I know with our e53s we would drive when cold but just drive quite slow for the first mile or two while the transmission was warning up.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)