Yesterday, I installed new oil cooler lines on my 98 Chevy K1500. It was a pain in the ass and I made a mess but I finally got it done. I drained the oil and removed the filter prior to doing the job since it was time for an oil change.
I also ordered a 20mm crowfoot flare nut wrench for the connections at the radiator since there is no room to get to them plus I didn't have any 20mm wrenches. It made the job a lot easier.
The lines that were on there were warranty replacements from the dealer because the originals started leaking while still under warranty. The replacements have been leaking for years but not dripping so I just left them alone. I used Dorman replacements this time with lifetime warranties so when they start leaking, at least the new ones will be free.