I have seen many discussions on brands/grades of oil to use, which have only led to further confusion on my part. This is my first Mercedes and also my first diesel. I have replaced the brake master cylinder and a rear caliper, so not completely mechanically challenged. The owner's manual recommends 10w40 and 10w-50 for year round usage. NW Ohio is very cold in the winter (sometimes in the teens or below), but relatively warm (80's-90's) in the summer, so I am looking for some recommendations on oil for summer and then later on for winter driving. Thanks, Alex.

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"Frau Blue Car" 1980 240D think Frau Bluker, cue the horses, formerly known as "China" from JimmyL
"Gunther" 1982 300D.....Turbo!! A/C!! Sunroof!!
"Fraulein" 1975 240D----Donated to NPR

Any 15W40 non-synthetic or 5W-40 synthetic is fine for year-round use.

Depending on miles driven during the year, personal preference, etc., you might consider a non-synthetic during the summer (less expensive) and a synthetic during the winter (better cold flow characteristics, easier starting). Fewer miles driven, consider a synthetic and change it once a year.

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970