Oil gets hot just like antifreeze. It will break down if it gets too hot, and will last longer if it kept cooler. If it's cooler it also stays thicker, and protects better. For more on oil; http://www.bobistheoilguy.com/
 The aftermarket has used oil coolers for years in racing and the factory has started using them on high performance models like mustangs and corvettes, and heavy duty applications like trucks and cop cars.
 There are 2 basic types of coolers. Oil to Air, and Oil to Water. Oil to air uses a small radiator to run the oil through, which cools it down. Oil to water does not mean the oil and water mix. It involves an adapter which has oil running one way and engine coolant running another. The 2 fluids transfer heat as they pass thru an internal radiator.
 Oil to water is used more and more by the factory as it has less parts, takes up less room, and is cheaper. Another advantage is that on cold days the engine coolant heats up the cold oil to allow faster warm ups.
 I decided to add a cooler to my car using a unit from the wreckers. Here are some choices.

 Some of the following photos were from the web.

 These are the standard oil to air adapters. They bolt in place between the oil filter and block. I don't know why they made the Chev piece so much taller.

 The big hex head on the ford is the cover for the bypass valve. A ball bearing and spring is unseated under higher pressures.
 The chevs' is under the square socket plug.

 Aftermarket adapters copy the ford style.

This arrangement was used in my mustang for a year or so. The hoses snaked around the rad support to the cooler. A metal strap was bent into an 'L' and bolted to the front and bottom of the rad support to hold the aluminium cooler.
The complete unit came from an LTD police car. Two fittings unscrew to allow cutting the hoses to length.
 I removed it to go to the other type and sold it for $100.00.

 Here is an angled adapter from a Ford van with a 460c.i. engine. It was used because the frame would be in the way of the filter. The 2 fittings are for the lines to an external cooler.
 It uses the standard ford filter but the filter stud has to be removed from the block so the hollow bolt can screw in.
 With this you can get the oil filter to be almost straight up and down.

 This is the standard Ford oil to water cooler. It is a Modine unit. It was originally used on turbo 4 cylinder Mustangs. It screws onto the filter pad and a shorter filter screws onto it. The 2 outlets pointed straight up and hooked up to the heater hoses. The copper color is braze as the insides are brazed together.
 More recently it was used on Cobras, hooked up to the heater hoses, and on police mustangs, hooked to the lower rad hose. On all V8s it lays on its' side with the outlets pointing forward.

 The 95 Cobra unit is altered a bit. The outlets have a 90 degree bend to make attaching the heater hoses easier. It also seems to have an additional bypass. From the factory the car had formed hoses and metal tubes, but ordinary heater hoses work. This is a rare cooler.

 The Explorer V8 adapter/cooler. It needs the bend to fit the crossmember. You can also see that the outlets are huge. They connect directly to the lower rad hose and the total water flow goes through the cooler.

 I thought about altering a standard type to this method of total water flow. Cut off the small tubes and weld in 2 big tubes with 90 degree bends.

 On the Modular engines Ford integrated the cooler into the block better. The lower rad hose attaches at one end but the exit is straight into the block.

 The Lightning supercharged truck also has a cooler. To fit it in they created a huge adapter/oil filter relocator/motor mount. I had a photo but can't find it.

 Next is the basic cooler on a Corvette. There is an adapter at the top for the chevy block. One line went to the blocks drain plug and the other tee'd into the heater hose.

 I don't think this is a cooler but an oil filter adapter. Corvettes needed more space by the exhaust so this allowed a narrower filter.

 V6 engines in 4WD trucks used a similiar unit that was a remote oil filter adapter and cooler.

( If you need a narrow filter on a ford use one from a chrysler 4 cyl. Ford and Chrysler have the same threads and O-rings.)

 
 Here is one that has unknown origins. It was on an engine that was literally laying on the ground. It appears that the oil goes straight through to the filter first, then throught the cooler on the way back into the engine. This is supposed to prevent clogging, or so the patent says.

 Here is some info on the engine it was on: DOHC 16V, block marked PK3, screwed in frost plugs, angled oil pan, penzoil filter PZI-33, serial B21A1 3701134 2-90.

   As I said, I used to have the oil to air type but I removed it. I decided to install a ford air to water type that I bought used for 5 bucks as a 'filter adapter'. I used oven cleaner and soaked it in various petrochemicals to clean it inside and out. Then it was painted with POR-15 silver.
 The choice was between hooking the coolant lines to the heater hoses or the lower rad hose. The heater hoses would be easiest. However the water would be at its' hottest, while lower rad hose has the coolest water. However on cop cars the hose was a special piece with 2 outlets formed into it.

   I went with the low rad hose. I built this adapter from a tube.  The smaller tubes were a single piece from an Audi air cleaner.
The tube was placed in the lower rad hose and the two pieces were lined up with the cooler and spot welded, then removed and brazed. Somehow the angles came out at about 90 degrees.
 Factory units have the 2 tubes inline and have 'S' shaped hoses, while this one uses straight hoses.
 The small tubes have small scoops inside. One faces forward and one back, to help pressure force water in and out of the cooler.
 The small welded bumps on the ends are to prevent the hose clamps from sliding off. Doesn't look like much but it works.

 Here it is on the car. My older bell shaped oil sender had to be redirected upwards with the bronze elbow you can see.

 I'm sure the oil cooler won't fit if you have an older engine with a mechanical fuel pump. The outlets would have to go right throught it.

 The disadvantage to this set-up is that on cold days the oil receives no heat until the rad is hot.