every 30000 miles for fluids is the service manual recommendation for the w126's I would recommend 30000 or two years for the fluids (radiator, tranny, diff and brake fluid)
Oil they say every 7500 but I would recommend at least 5000 miles.
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)