Very timely, I was wanting to do the rubber brake lines on the 300D as the rubber is starting to show fine cracks all over. I tried and the flare nuts are on tight.

Will be trying heat and penetrating oil.

The inner part of the fitting also gets rusted to it. Twisting the steel line sometimes. Things get pretty rusty where I live so I always heat things up to avoid that as well. What is required varies by area. The heat and cool three times rule is used in many places. Especially on bleeder screws.

Ya, heat is very important to success a lot of the times. Even though heat often burns off the Oil when you re-spray the Oil the warm parts allow the Oil to get in better.

If you can get the line off with out damaging anything after you clean off the rust you can slide the nut back and coat the exterior of the line with a thick coating of Never-seize and then slide the Nut back on so that the inside of the nuts also gets coated and wipe off the excess. That usually keeps it from rusting again.

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84 300D, 82 Volvo 244Gl Diesel

If you spray on PB Blaster (Homedepot sells it but it comes with out the little tube) or forum members claim Kroil is even better and can do that multiple times over the course of a week or two you may not need any heat. But, even if you are using a flare nut wrench you need to decide if you think you are getting close using too much force on it.

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84 300D, 82 Volvo 244Gl Diesel

Thanks for the tips! I am actually wondering if I should just split the flare nut with a dremel, I think I will need to remove the clip holding the steel line though. I've decided to go ahead and order the clips in case it comes to that, together with the rear brake lines, just in case.

You would split the Female end of the Brake Hose (which of course ruins the Hose) that the Brake Line Flare Nut screws into.

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84 300D, 82 Volvo 244Gl Diesel