How is the capacity of these oil pans measured?
 

My stock oill pan capacity shows to be 5.5 quarts...it's pan #12614821 (Hummer Pan).

I'm trying to determine the capacity now after it's been modified. I already have 5 quarts into it, and it's still got about 1 to 1.5" left to go until it's at the top of the pan.

If I fill it all the way up, it's going to have more than the advertised capacity, which isn't possible.

So.....................does anyone know how high up the pan to go when determining the volume?

Measure how far down into the pan the dipstick full mark is.

I just thought of that right after I posted. I can't believe I didn't think of it before hand.

The best way is to look up the capacity, then fill the pan with water after you level it up.

Mark where the water line is.

Modify the pan then pour water into it to the line - thats the capacity

oil pan capacity
 

When gm designed their pans the idea was to keep levels well below the rotating assembly to minimize parasitic losses and to promote better bay to bay breathing. Most production oil pans are capable of holding an additional 1-2 quarts above dipstick levels. You will notice that even on the f-body pan that the oil level sensor is approx. 2 inches below the pan rail confirming this concept.Early LS/Gen3 engines had some issues with bay to bay breathing but a redesign was made to improve this by putting windows in the main caps.Keep in mind that when the engine is operating 2-3 quarts of oil are in constant cir culation which drops oil levels in the sump well below the rotating assembly.These ideas/concepts were used in developement of the LHX oil pan sold by RetroLsx,Carshop,Dirtydingo Motorsports.You will be fine with 5 or even 6 quarts but I would suggest using a windage tray to help scavenge any oil that may get up into the rotating assembly.You will also have to remark your dipstick accordingly.