Not my only source, but my best one. The other two are dicey at best. (Had another, but lost it already do to going out of business.) But I am getting oil from them at present. I am still looking for a couple more sources.
I am not sure of what it was that fixed the priming issue. I found a small leak in the hih on the suction side. Fixed that. Then had two leaks on the top of the tank. One is still leaking a bit, but not as bad. It is an old level indicator. The gasket is leaking. I am going to replace that with another, so I am not going to great efforts to fix it. I will just put a bit less oil in the tank. It was right at the top of the tank, which is where the gasket is and was sloshing out around it. I was able to turn the screws a bit tighter, which helped some.
The other leak on the tank is at the hot fox. The screws had loosened up and oil was sloshing out around it as well. Tightened those down as well.
The 3rd or fourth if you count both leaks on the tank separately, was the hot fox itself. The person helping me with the install, put a small screen at the bottom of the hot fox to keep stuff out. I told him I didn't see the need as I was bringing it down to 2 microns anyway, but he insisted. I removed that.
I hear the two leaks on the top of the tank would not have affected the pump prime, so I am guessing it was either the leak in the HIH, or the screen in the hot fox.
The one thing I did find out for sure is that there was not crud in the bottom of the tank and no signs of water. More concerned about water than anything as far as oil quality goes. I was glad to see only oil.