25 Nm is about 18 ft.lbs I think. Not a lot of torque. 'Snug' is the best definition I can think of for a setting that low. I set my torque wrench to 20 an go just until I feel it start to click and I get no leaks. Small 3" or 6" extension should be cheap, non? If you are strong enough - hand tight could deliver 18 ft lbs too. I think it just seats the 'O' ring.

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dtf
1994 E320 Wagon (Died @ 308,669 miles)
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