^This

Per GM:

12557752 Blue- used on oil pickups WITHOUT locating groove in tube
12584922 Orange- used on oil pickups WITH locating groove in tube

The LS6 and LQ4 use the same oil pump

 

Thanks atomic and robert

I am going to buy an orange o-ring which I think is what I already have.

 

any update on this? I have the same problem.

 

Ya
Go with the orange oring.

 

Is it more of an orange or a red. I have a blue one and a red one. what year is the orange one for? My donor block was a 2003 6.0. And a Katech LS6 pump with tube from the donor.

 

The o-ring will be specific to the truck pickup tube, as Atomic already explained.

The factory O-ring on my 02 LQ9 was GREEN, however, the replacement from GM was orange/red. The blue one is for the car engines I believe.

 

As far as I know there is only two.
Blue or red/orange

I think the red turns orange after a while

 

I got mine fixed. The o ring that I took off was orange and lose fitting. I replaced it with the red and is all good now. I had the green, black, orange, blue, and red just to finally fix this annoying valve train noise and low oil pressure. The green fit tight but fit the tube lose, the black was wobbly but fit the tube, the blue fit the tube but was lose and wobbly, the orange fit the tube really well be didn't seem to seal in the pump. I tried the red last and it fit perfect on the tube and in the pump. Nice seal so I went with the red. I got it all put back together and the engine sounds great and my oil pressure at idle is 50-55 psi..

 

this came with my Melling pump