I'm changing the oil on my Stelvio, and I can't seem to find a cap-type wrench that fits the stock filter properly. I tried my old-style BMW wrench, and it's too small by about 1-2mm. I went to my local auto parts stores, and the 74mm is too small, and the 76mm too large. Unfortunately, they don't list a 75mm wrench. Is there some special Guzzi wrench you have to buy?