Oil line plug/ low oil pressure on cold starts

The lifters are Lunati Micro-Trols. When I installed them, one of them didn't pump up and I replace it with a new one. Yesterday I noticed that another one wasn't pumping up. The cold start issue has been essentially the same since I fired the engine up in the car for the first time. However, I just noticed a smallish coolant leak coming from the intake and found some coolant in the oil - not a lot and definitely not completely milkshaked. I drained the oil and it looked ok. So now I'm going to pull the intake to fix the coolant leak. Lunati apparently is not making lifters anymore, so I will have to fix it. They have snap rings, but my crappy snap ring pliers won't grip them, so I'll need better ones. I will try 5W30 oil and maybe even synthetic. I don't even want to ask this question, but any thoughts on something like the Lucas Heavy Duty Oil Stabilizer? I will need something with ZDDP though, right? Any recommendations?