No recommendation at this time. I was planning to do it on my diesel too but
lots of things to do that it is not a priority.

I woudl suggest doing a lot of research on kits and how the systems
work before purchasing anything. I did my reserach on two forums. one
is at http://biodiesel.infopop.cc, and the other is the forums at
frybrid.com. I had originaly intended to research which kit is better,
but the more I learned about the kits, the more I figured out about
just how simple they are. It can be quite complicated ifyou try to
figure out what is the best way to do stuff, as there are many
compromises to make and solid arguments for both sides of each
decision. However, the fact that even amongst the best kits there are
differences in their philosophies tells me that none of the arguments
about which is best really hold that much water.

With that said, I'd suggest that if you are mechanically inclined,
research, design and build your own. It will be cheaper, easier to
troubleshoot, and probably work just as well if you are good. If this
doesn't sound like the solution for you, the greasecar kit is a great
kit for the money. It uses hose in hose, which gives better thermal
conduction than hose on hose, is relatively cheap comapred to others,
and is a relatively simple install. The drawback of this system is
that in many cars it still won't get the oil up to the 160-180 that
you want. That can easily be remedied by installing a flat plate heat
exchanger(FPHE) that you can get for about 80-100 dollars. Then you
have an excellent system for well under a grand. If you want to go
higher tech with alarms and stuff there is the frybrid system. It is
electronically controlled, but almost twice the price. Some people
aren't big on Chris, the owner, and I've seen him be quite rude to
people on forums, but then again, the other people were also being
quite rude.

I think Tiger mentioned that you have to switch fuel injectors. this
is not true with a two tank system like the two that I mentioned. In a
single tank system you do have to do that, but I know very little
about them except for there is a company called elsbett based in
Germany that apparenlty makes high quality kits.

As far as the car beign a good car or not, the general opinion is that
the mercedes peaked in quality in 85. They had finally worked out
almost all of the bugs.(except for the radiator overflow tube nipple
breaking off the radiator on every one of them I have ever seen.) Then
in 86 when they switched to the aluminum head engine it reduced
longevity. Apparently if you let the AL head engine overheat you are
done for. So I'd say you're fine if you're the kind of driver that
keeps an eye on the coolant temp. I don't intend to make you paranoid
to the point of watching the gauge obsessively, but if you don't think
that you'll ever let it overheat, then you will likely get a lot more
good use out of it... As long as the old owner also didn't let it
overheat.