I strongly disagree with the suggestion to use any type of gasket sealant on that gasket. The OE gasket is designed for all the sealing power that is necessary. It may have leaked due to the application of the gasket sealant.

Getting every last molecule of the old gasket off the ground face on the block is mandatory.........or you'll be doing the job twice. If you don't spend at least one hour with a single edge razor blade and some gasket remover, you're not doing the proper job.

A couple of more tidbits:

Get yourself a 1/4" gearwrench (because I've never seen or heard of a 6mm).

Then get a 6mm allen key and cut it twice at the bend. You should have one piece that's 3/4" long and one piece that's about 4" long. For the top three screws, use the 4" piece with the gear wrench. For the lower two screws, use the 3/4" piece with the gear wrench. Don't get any ideas about using a socket wrench with a 6mm hex bit. That's not happening. This one tip will shorten the job by about 1 hour.

BTW, the top three screws must be accessed from the top and the two lower screws are accessed from underneath the vehicle.

One other problem:

When you reattach the oil line to the turbo, it may not thread by hand. Don't force it with a wrench. Since the line has a multitude of bends on it's way to the turbo, it may not be a perfect fit. You're forced to undue the clips all the way down to the turbo, and, may need to unbolt the line at the turbo to get the fitting started at the cooler. Be best to have a turbo gasket available. Don't skip this step and force the threads on the oil filter housing.

It would be beneficial to have a new aluminum sealing ring for the turbo oil line fitting. The old one will probably be mangled pretty good.