Just as a reminder, it's a slow and tedius job. You can't clean the rad in 30 minutes due to the multitude of fine passages.

I have not mastered the art of the cleaning yet and will make an attempt with condenser cleaner, and, possibly some pipe cleaners.

Hold the radiator up to the sun and look between the passages..........you'll see what your task will be. When you get done, it should be perfectly clean through the passages..........not an easy task by any means.

If you have any tips after you do the job, please advise.

BTW, a temperature of 100°C. is nothing to be concerned about. Two of these will also bump 100°C. on any significant load.