I just bought a 1981 300TD and checking the oil level is driving me a little nuts. If I do as most of you suggest, wait 5-10 min after turning the engine off, sometimes the dipstick say I have no oil in it at all. But if I wait several hours the oil level shows that it is normal or overfilled.

What gives, does it take that long for the oil to drain or do I have another problem? I drive back and forth from central Texas to Arizona, 1100miles each way, once a month and have been changing the oil after every trip thinking that there are sludge deposits and this will clean it out. I have done this 4 times in the last 3 months.

I use 15-40w oil and change the filter each time.