Question... The standard oil coolers, are they prone to putting oil into the coolant? Reason being I don't have a warped head, the block isn't cracked and the head gasket wasn't blown.

When you say "standard", what do you mean? Aftermarket? Factory? What car?

Typically, an aftermarket oil cooler is air-to-air (not air-to-water, like a radiator), so there's no way it could get contaminated unless one of the three scenarios you mentioned above are, in fact, in existence.

Have you done a compression and leakdown test?

I can't think of any other way to get coolant in the oil.

Welcome aboard!

Thanks for the welcome.
The standard little water/oil disc one under the oil filter. Or at least that's what's on an Australian engine. LOL. And the engine came out of an S14 I think, not sure, I'm putting it in a 1600.

The standard nissan oil coolers are not commonly known to cause a mixture of oil and water, but it is not impossible. I have personally seen one come loose at the large nut-like object on the top of the housing and below that nut-like housing is large O-rings. If there is no mixture in the block's cooling passages, no mixture in your head nor radiator, I would lflush it out and start over fresh. Be sure to make certain that your oil cooler housing is not loose and let us know how it goes.

Thanks. It will be a little while as I'm working on the body atm. I paid bugger all for the engine so I guess at some point I will have to pay to get it all professionally tested.