PeachParts Mercedes-Benz Forum - View Single Post - 603 Motor

Jeremy5848 · #20 06-12-2012, 04:05 PM

My '96 E300D (W210, OM606NA) was on dino oil/filter changes at 7500 mile intervals for the first 248,000 miles and 3 owners. The first 200,000 miles was all dealer service (1st owner) and indy/DIY service after that (owners 2 and 3). At the first service post-my-purchase (4th owner) I changed to Mobil-1 5W-40 and have an additional 36,000 miles on the car at this point (284,000 total). No oil leaks before or after changing.

Because the car is driven only about 8,000 miles a year, I made a command decision to change oil and filter once a year. Oil tests over the miles/years have consistently improved (show less wear) and the following picture shows the insides at 277,000 (~4000 miles on the oil) -- clean and with no observable wear. Original timing chain, too, it will probably outlive me.

I plan to switch the new-to-me 1995 E300D (W124, OM606NA) to Mobil-1 at the next oil change, due in another few thousand miles. It also has (at 191,000 miles) no oil leaks and I trust it will stay that way. If the engine had some leaks I would be more cautious about making the switch to synthetic.

The concern about existing leaks getting worse with synthetic oil appears to be valid. My indy says that the synthetic oil molecules are smaller (fewer carbon chains per molecule) and thus can get through gaps that will stop a dino oil molecule. Be that as it may be, I switched the transmission fluid in the '96 to Mobil-1 and the existing front pump seal leak worsened to the point where I finally bit the bullet and had the transmission overhauled.

The rebuilder said that all of the hard parts were good and the wear parts would have been good for another 50,000 miles (total transmission life would have been ~300,000 miles). Oh well.

Jeremy