What kind of oil change interval would you guys do on the following cars? I've decided to go with two year intervals unless I'm really missing something. Using synthetic in the SLK and the ponton, dino diesel oil in the 240D. Mann or Hengst filters in all. Oil analysis on the ponton and the SLK show that the oil is in good shape after two years.

SLK - 2000 - 2500 miles a year
Ponton - 750 - 1000 miles a year
240D - 250 - 500 miles a year

__________________
Len
'59 220S Cabriolet-SOLD and living happily in Malta
'83 240D 351,500 miles original owner-SOLD
'88 560SL 41,000 miles - totaled and parted out
https://sites.google.com/site/mercedesstuff/home
'99 E300 turbo 227,500 miles
'03 SLK320 40,000 miles - gave to my daughter
'14 Smart electric coupe 28,500 miles
'14 Smart electric cabriolet 28,500 miles
'15 Smart electric coupe 28,000 miles