I sent an email the MBUSA and this is thier response on the topic of no oil pressure indication on a ML....
Thank you for your recent e-mail.
If there is no oil pressure, the engine oil level warning lamp will remain
on. If after checking the dipstick, the level of oil appears to be
appropriate but the light remains on, the oil pressure most likely is the
reason. You would need to have it diagnosed by the dealer but that would
be your indicator.
The opportunity to correspond is appreciated.
Hope you all find this helpfull......and I hope it is correct
