1. Spark plugs: I checked the gaps in all plugs and ran into this problem: Plug No.2 was almost impossible to get out. I used a braker bar, penetrating oil and hot engine (cold did not work at all), and this was the only plug which only came out with hard work until the final exit; after gapping, it did not want to go back in, either, so I only screwed it in about half way, and it was tough all the way. Now that I bought new plugs, what should I do? If this was the symptom of a cross-threading, I rather screw the new plug also only half-way in and not have the expense with heli-coils, etc. Is there anything major wrong with this approach? The car is not driven very much. By the way, the threading of the difficult plug did not show any signs of damage/stripping or dirt, so I assume whatever damage there is is in the block, and a new plug will also stay in tight.

2. Anti-freeze: A couple of years ago, an independent shop specializing in Mercedes replaced the radiator with a Japanese, generic one and used Peak-anti-freeze (the green stuff) to fill it back up. When I asked about Mercedes' anti-freeze, they just made fun of it, saying that it is a scheme to make more money, that the green stuff also has all the protection additives for all the metals used under the hood, etc. What is the final wisdom about this? What chemicals would Mercedes use that nobody else does? I am coming up to a renewal of the coolant, what should I do and why? Somewhere I saw a reference to a cheaper alternative, Zerex-brand from NAPA and Autozone and the containers don't say anything really different from Peak or Prestone, anything else?

3. Brake sensor: One front brake sensor wire is broken off too close to the caliper to fix the wire. I assume that this does not affect the ABS, so I should be ok if I check the pads every couple of years. Anything wrong with my thinking? How could I reattach the wiring?

4. Distributor: My shop manual shows a vacuum advance attached to the distributor, but there is nothing on the car, and nothing seems to be missing. Do I have the wrong distributor?

5. Timing: The timing seems to fluctuate a little; it was a lot worse before I found a broken vacuum-thermo switch (50 degrees) and replaced it. Is there another place I should look for something wrong?

Any good advice is appreciated, thanks!

1. Spark plug not threaded all the way in will not ignite the air/fuel mixture properly. Steel and aluminum never mix. ALWAYS use a dab of never seize on the sprak plug thread when putting spark plugs in an aluminum headed motor.

2. My MB mechanic has been on his own JUST fixing MB's for 16+ years and told me there's no difference in green or MB that he's seen. Brainwashed others will tell you different.

3. Brake sensors only tell you when the pads need changing. Just use your eyes.

4. Probably wouldn't run with the wrong unit.

5. Not sure.

1) Chase the hole with a tap and try again.

2) MB has used alum radiator cores for over 30 years and their spec coolant is soecifically designed for that metal rather than with copper cores. Zerox makes the fluid MB markets in the US. It's yellow.

3) Brake sensors cost about $2. Put a new one in. Takes maybe 1 minute.

Here is a place to check for your broken sensor. BTW I am not affiliated with it!

www.getmercedesparts.com

You can get all (3) new ones here and still get some change back compared to purchasing one at the site above. The link is for my 99, the sensors have been the same for over 20 years. http://catalog.peachparts.com/ShopBy...e+Pad+Sensor&m

I got MB pads and sensors for all four wheels for my SDL for $50 on e-bay a while back. Deals can be had if you look!