Don't use Mobil 1 in your Marzocchi. Like Nate said, go to your local motorcycle shop and get some 125/150 (7wt) synthetic fork fluid. If they don't have that, get 5wt and 10wt of the same brand and mix equal parts to make 7wt. Just make sure when mixing oils to use the same brand. Look for brands like Golden Spectro, Silolene, Maxima, BelRay, etc.
And if you absolutely positively can't find any of the above, some people use Automatic Transmission Fluid (ATF) in their forks. It's a bit thicker than the regular Marzocchi oil but would probably work okay especially if you are a heavier rider.