Newly acquired 92 300TE 4matic with 33,000 original miles. Deciding whether to replace original-fill fluids in front and rear differentials. Do these fluids deteriorate over time (like brake fluid) or can they remain in the car until the recommended 60K mile replacement?
I realize that it couldn't hurt to do it, but would it hurt not to do it?

You really won't know unless you sample/inspect the oil, which is likely more costly than changing it out.

At 33K the car should have had fluids changed anyway. Since you're a "new" owner, it's the perfect time to refresh ALL the fluids and filters and start keeping good maintenance records.

Differential fluid should be changed every 30,000 miles ... same for transmission fluid.

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Fred Hoelzle

It's only $10-15 bucks worth of oil--do it anyway.

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Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
Two BMW motorcycles

I figured that's what everyone would say.
By the way, MB specs a special hypoid fluid for the rear differential which runs about $35/liter. Front diff. takes the standard hypoid since it's a non ASR differential.

Change it, I do diffs at 25K like the trans, easier to keep up with at those intervals.

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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]