You might just consider buying one from the dealer...they are not that expensive (under $40 as I recall) and you'll need the locking tabs for the filler tube anyway if you don't have them so you'll need to go to the dealer anyway. Since the fluid itself is costly, and the labor is cheap if you're DIY why not spring for the proper tool and not jeopordize your transmission to save a couple of $$$?

In answer to your question, the 722.6 tranny takes a special synthetic fluid, available from the dealer (about $11 per liter IIRC). There is a proper way to check it using the temp sensor in the transmission, but that requires the dealer "star diagnostics" so most people just drive until the tranny is hot (but it should be at precisely 80C) and check in gear on a flat surface. You can also check it cold as there is a set of marks for 25C (77F) temperature as well.

If you have no way to check the temperature accurately then I would suggest you do it cold and use the cold markings since I have heard that if you check it hot and it's not at exactly 80C the level reading can be way off.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz