GMC Repair: chev duramax diesel lb7 no oil pressure, allison transmission, duramax diesel

Question
2001 Chev Duramax Allison Transmission 56,000 km – after oil change “check oil pressure” light is on for between 5 to 30 seconds.  Oil and filter changed twice since but no improvement.  2 suggestions are that:  oil pump needs replacing or oil pump looses prime.  There is possibly a correlation between the time intervals depending on the incline on which the truck is parked; rear is lower produces the larger time interval; rear is elevated produces the lower time interval.  Also, when the truck is restarted after warming up or driving, the “check oil pressure” light does not appear.  I cannot accept that the oil pump is faulty under such described circumstances.  Expert opinion PLEASE.

Answer
Hi
I will do further research on this problem. I have found 2 items that MAY or MAY nothelp.
1 is too much oil in crankcase will cause the described condition.
2 is the oil filter.
Take these as suggestions. I will do a bit more checking.
Please follow a private post with your email addy, so I can contact you directly.
Thanks
Pawl