I've had good luck with felt washers that go around the batt posts before you reinstall the cables -- catch the acid leaking out around the posts, eliminate the corrosion build-up. $2-$3

There's often an overflow tube on batteries -- make sure the supplied hose -- or a longer one -- is installed, to keep any acid away from sheet metal.

My old dad (may he rest in peace) used to soak the felt washers in hot vasiline. Then clean and wrap the post with masking tape, put the washers on, remove the tape then put on your clean clamps. It is a bit of a job, but you do it once and you don't have a slow short across a damp battery top again for the 5 or 6 year life of the battery. Isn't it funny how as the years go by we more and more respect the experiance the old guys had.

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Thanx,
Alberta Luthier
1983 300CD ('Stinky')155k miles, 2.47 diff, EGR removed, AAZ injectors with 265 nozzles from Sean,and vogtland lowering springs.
1984 300SD ('Old Blue')150k Klicks from Japan originally, came with rear head rests, no sunroof and never had an EGR

Well, it is really up to you. There are obviously some advantages to buying one of these gel batteries - I am assuming that is what this is. But if the only thing you are concerned with is avoiding corrosion caused by leaking acid, then you could probably just grab a lead-calcium "maintenance free" battery at a much cheaper price - these are sealed, so they can't leak and they are more resistant to corrosion.

One the other hand, the gel batteries last much longer and can be deep cycled several times without killing the battery - they do have good qualities, which is why you pay so darn much.

Personally, I just go with the mid-range. A lot of batteries now have 1 year full warranties and then are pro-rated for another 5 or 6 years, just hold on to your receipt.

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'95 E300D ("Tank") - 231,000 miles
'79 240D ("Biscuit") - 197,250 miles (Sold)
'83 240D ("Ding-Ding") - 217,000 miles (Death by deer)
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"Back off, man. I’m a scientist” ~ Peter Venkman