I am pretty sure we discussed this previously, but I couldn't find it. Do I want my oil cooler with the lines connected to the bottom, top, or sides? I'm looking for inspiration, as the cooler just isn't magically fitting anywhere and I'm going to have to work to get it in the car and still keep it kind of out of sight.

The return line should be on top so you can "burp" it to get rid of the air, and so that any bubbles in the system can be flushed (and not trapped in the core).

my 95 GMC Van has one and it sits atop of the oil filer the lines run to the rad.This is a factory doing.

Uggh. I knew you were going to say sideways, because that is going to be hardest.

If sideways is unreasonably difficult, run it with the hoses "up". It's not preffered, but will work.

How picky your cooler is about bleeding all the air out of itself depends alot on what kind of cooler you have.

The tube style coolers are much more forgiving about that than the Plate & Fin style (but the plate and fin are a better heat exchanger by far).

I have run a tube style cooler with the fittings down, but I would hesitate to try the same thing with a plate & fin cooler; if the cooler has the full flow.

If it's a partial flow, or bypass, I've done that too.

X2 - the plate type is better as to heat rejection (needs less total cooler, and less surface core presented to the atmosphere), but I suspect the internal shape allows a bubble to become "flat" and just refuse to change back to round to get back out.
You can just break the line at the exit to get any air out after initial start, but a bubble caused by uncovered the pickup or aeration is harder to purge.
I've read that an infra-red gun can tell you if there an air-lock problem because the plates will show different temps (the upper plates will be cooler since no oil passes through), but I haven't done it.

When we ran Legends Cars, the factory had a dual cooler setup, the engines (Yamaha FJ1200 motorcycle) had a 2 stage pump.

One stage was excluxively for an oil cooler that the bike had.

The factory (600 Racing, factry for the Legends, not Yamaha) was marketing a dual cooler (2 seperate units) when we started that kept the oil seperate (the "cooler" side of the pump returned the oil to the pan).

I didn't notice a significant change in oil temp from having the lower cooler hooked up, to having it bypassed (the one time I tried it, due to damage to the lower cooler, from a mishap in practice ), the factory setup mounted it upside down (Setrab, plate and fin Model# 910-6).

Excellent cooler, others mounted it in different places with (claimed) great success (and the fittings not pointing down).

This leads me to believe a significant portion of the cooler core was filled with air on that one.

By the time I had that figured out (kind busy with other stuff) I was running a Fluidyne tube style, with the oil coming in on one end (on the top) and out the opposite side bottom to the mains, with an oil line (dash 3) to the cams out the top, opposite of the oil coming from the filter (oil cooler in).

As a tube style cooler it was kinda odd, so here's a pic.



As I swiped tht from the Fluidyne site, here's the link to that page: http://www.fluidyne.com/pl_legends.html

It was the best setup I actually tried, with the line to the cams it was self purging, as the air had somewhere to go, and with the small line to the cams, the mains got the lions share of the oil (as they should).

FWIW the factory came up with progressively larger coolers, including multi pass ones.

The hot setup when we stopped being a dealer was a "920 3 pass", I wanted to try one but we were selling them faster than we could get new ones (people were upgrading) so I never got the chance to try them.

They sure looked impressive.

Point being, in my admittely limited experience, plate and fin, with the fittings pointed "down" is not the way to fly (air lock city ).

However they don't seem to care if the fittings are sideways, or pointed up.

I am installing a B&M supercooler (plate & fin), full flow with a thermostat on it and electric fan. So I'm definitely going to make sure its hoses are on top then. Thanks, guys!

I don't think it matters -- the oil will flow fast enough to push the air out.