For my 07' TLS I have established the following schedule:

Oil & Filter changed by dealer every 5,000 miles (Originally Mobil 1 synthetic used but dealer switched to Agip Synthetic) I also add 1 bottle of "Tufoil" additive each oil change.

Tires Rotated @ each oil Change (Every 5,000 miles)

I changed Air Filter at 20,000 miles but it was very dirty, so I change now every 15,000 miles. It was changed at 35,000 miles, 50,000 miles & will be again at 65,000 miles.

Trans fluid is changed by dealer every 20,000 miles.

Cabin filter changed every 30,000 miles

I don't think it is difficult at all to take care of your TL. I know using synthetic oil isn't cheap, it costs me $80 at the dealer for that alone but I plan on keeping mine a long time since I just paid it off. I already replaced my front brake pads twice & the fronts discs once which was expensive.

 

I thought cabin air filter was every 10k. Why not save money and just do the oil change and transmission change yourself? Z1 sucks donkey balls.