For non diesel maintenance tips, and also ANY W126 questions, try the W126 section (I am a moderator there) of
www.benzworld.com (best place for the W126er freaks,
and also, give a look at the buyer's guide in
www.mbcoupes.com for some maintenance suggestions (I co wrote it back in '98 but it is still pretty good.)
The Diesel Discussion section here is perfect for questions about the cars, too. Real serious knowledge is there. It is "the" place..
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1991 560 SEC AMG, 199k <---- 300 hp 10:1 ECE euro HV ...
1995 E 420, 170k "The Red Plum" (sold)
2015 BMW 535i xdrive awd
Stage 1 DINAN, 6k, <----364 hp
1967 Mercury Cougar, 49k
2013 Jaguar XF, 20k <----340 hp Supercharged, All Wheel Drive

(sold)