5 years ago right after buying my 87 300D with a #14 head I bought a used #17 head just in case. Now that the #14 is blowing smoke out the coolant bottle, its time to rebuild that spare #17 head and pop it in. The seller failed to mention that the #17 head was heavily coated in WVO residue. I got the injectors out pretty easily but but the collar nut won't budge. I'm using acetone to dissolve the WVO goo which is pretty damn effective but the nuts aren't coming out. All the torque in the world and even an impact gun can't do it. I only removed 1 nut and damaged it in the process. I can deal with all the visible WVO residue but I think its down in the threads and I can't get to that stuff with acetone, it evaporates too quickly. I need some better ideas before I start doing real damage to this thing. Yes I, using the correct screw in collar nut tool.

The one on the left is cleaned out with acetone and not coming out. You can see where the keyway in the nut is getting bent because I'm applying so much torque to it. The one on the right isn't cleaned out yet. Ideas?

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CENSORED due to not family friendly words