Yes breaking the crankshaft bolt lose is the deal breaker. I invested in the high torque Milwaukee 1/2 inch cordless impact to tackle the job as that is an extremely tough but to crack.That's very low for a 2007!! And here I thought my 2007 was low sitting at 88,000. It's also due for a timing belt. My only concern is getting the crankshaft bolt loose.
Tried a standard 19mm impact socket and full beans on the adjustable Milwaukee and the Honda just laughed. Knowing this was an issue, I already purchased the Lisle very heavy 19mm special socket for the Honda/ Acura crank bolt. Took the bolt out like it was nothing.
Highly recommend a similar set up for anyone doing this job.
Only tools need are the bar to lock the cams in place and an insert to lock the crank. Can be had for less than $250. Even with the special tools, the DIY savings are significant.Expensive special tools required for German cars.
For the timing belt, water pump, tensioners, etc in the A8 requires putting it in service mode. Which pulls the full front clip off the front if the car providing nearly full access to the face of the engine. Making things much easier.
I have another 25k miles to go so it will be a while before taking on the chore.