There is a move to lead-free solder. The so called "RoHS" requirements went effective last July. There are exemptions for many industries including automotive, however not all companies use all the exemptions. The European manufacturers have been early adopters of environmental practices.

You are making 2 different points here:

1) 'When resoldering you should remove all the old solder and use new solder'.
You are absolutely correct. 100%. This is exactly what should be done. I mostly use a "Soldapult" solder sucker, but wick also works fine.

2) 'Lead solder is "better" than lead free solder'. Strictly speaking this is not correct. I have seen no claims from anyone in the industry that lead free solder is inferior to lead solder. However, it needs a higher temperature and there are several different alloys being used, so from the point of view of the DIY'er (including me) I use tin/lead 63/37 solder. This is also sometimes known as Eutectic.

As I believe I previously stated, the trouble is in the single sided PCB with no plated through holes. This type of board is cheap cra* that does not belong in a Mercedes. It doesn't belong even in a Hyundai IMHO. These boards WILL fail in industrial applications or in any application with heat cycling such as in TV sets etc.

So, remove the old solder, clean the area with a clean toothbrush, use new 63/37 lead solder.

Mike

__________________
1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra