7.3 oil pressure prob. Hard starting

[nevr2low93]

So I haven't had a diesel long and don't know anything about them. I have a 99 7.3 with 230xxx miles. It broke down this a.m. At first I thought out of fuel because it had 1/8 of a tank registering, but then went down below "E" when I pulled out the driveway. I put fuel in it. And also noticed it was 8 qts low, so filled the oil up too. It wasn't even touching the stick. I finally got it to start, it ran rough for a sec and then cleared up. It runs and drives great but if I shut it off and leave it sitting it takes a long time spinning over before it builds oil pressure and will start?