John, thanks for the reply!
CDR has been cleaned and serviced. Maybe a quart a week is a high estimate, maybe a quart every two weeks. I haven't really paid attenion, I check my oil every few days and top it off about 1/4 quart each time. I pour from a gallon jug so I'm not positive on my amounts each time...
I hear ya on the guages! My fuel guage has never worked, but I did get my water temp. and oil pressure to work with new sending units. I'm still saving up for good mechanical guages. I've been pretty confident with the oil pressure gauage working correctly.
The fuel system has about 8k miles on it, and I've gone through 4 sets of return lines kits between switching it over the current truck, doing the head gaskets, then fixing leaky o-rings twice. Between all the switching I've torqued the Injectors down equally with new copper gaskets each time. I will check if they're loose or have bubbles of fuel seeping out the threads.
Fuel filter is about 6 weeks old, I put a new one on when I did the head gaskets.
I had been running a quart of ATF in each tank except for the last 2 fill-ups, just because I was rushing. I'll remember from now on.
I did forget to mention the cold start in the morning was fine. Sounded perfect, and the oil pressure gauge bult up pressure like normal and no knocking sound.
I've mixed up my facts, the afternoon start was actually a warm start, when the oil pressure didn't build quickly and it knocked.
All in all, I'll keep my ears open tomorrow. It could just be a freak thing. I just wasn't sure if the oil pump was giving me a warning sign of failing in the near future...anybody have an oil pump fail?