time is money. your time is money. many of today's businesses contract out services they need to other companies. same for keeping up an older mercedes. there are a few items that at least for me, I contract out to
others. one of those is the vacuum system on a merc diesel. unless you
have a lot of time and patience, a vacuum leak can test anyone's patience.

when a leak materializes (and they always DO), I take it to a trusted indy
and let them track it down. my time is worth more doing other things.
ditto for transmission repairs, motor mounts and air conditioning service. other than that, you can learn to do most of it yourself and save
yourself a boat load of money. I concur on the bio decision. stick with
#2 diesel until you really understand the car.

TWO IMPORTANT ITEMS: in cold weather be sure and add a diesel
anti-gel additive to the fuel tank, otherwise you will regret it. if the car
doesn't have a block heater, install one. you'll need to plug it in in
cold weather conditions, otherwise the car may not start. ALSO,
never use WD40 in the air intake unless you want to snap a timing chain (can you say expensive?). best to keep a full tank of fuel in cold
weather conditions. ask me how I know about this one. diesels
run hot and they don't like cold weather starts. if you have a heated
garage, all the better. at a bare minimum plug in the block heater
and keep that baby warm. carry a 100 foot extension cord for situations
where the car might sit out in ice cold weather conditions.