I'm in the process of swapping out my oil cooler hoses. Had an unusual experience with the nuts on the cooler end which may help someone else. A few weeks ago I tried to loosen the nuts on the cooler. No go. Put PB Blaster on them and waited a couple of days. I then put the 1 1/16" wrench on them and tried to loosen them. I used far more torque than a person should use without a back up wrench and especially on an aluminum part. I did this because I have a spare cooler in the basement and I figured if I broke something, no big deal. Nothing moved. Nuts seemed welded to the aluminum. I planned to cut the hoses, remove the cooler and deal with them off the car. A couple of days ago I tried the top nut again and it came loose with virtually no effort. This morning I tried the bottom one and the same thing happened. Came free with just a few pounds of pressure on the wrench.

Not sure of the physics of the situation. Did the PB Blaster eventually work? Did the very high torque I applied days ago have some effect on the bond between the aluminum and steel? The car has been driven in the meantime so it has gone thru multiple heat/cool cycles. But in any case, it's worth mentioning because those nuts can be a ***** to remove. I had to use a dremel to cut off the nut on the one I had in the basement.

So, if you want to give it a try, put some penetrant on the fitting and wait a few days. Torque the bejezzus out of the nuts trying to get them off. Let them sit for a few days and try again. My case may have been a miracle, but that seems unlikely since both nuts responded to the same treatment.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13