I have a layer of oil on top of the antifreeze in my radiator, there is also a ring of oil scum on the radiator cap base.

On the valley pan cover groove adjacent to timing chain cover there is a lot of antifreeze- This was not the case last week.

There does not appear to be any water or scum on the dip stick.
There is some scum on the top of the timing chain cover near the "long bolt" on the driver side

Also the heater hoses are sweating an thin oil coating?!?!!

I wicked off the oil in the radiator and it is clear with tiny threads of gray in the oil layer.The engine runs fine.
There is a faint ticking sound coming from the timing change/water pump area.

before you start your engine again you should drain a small amount of oil out of your oil pan. A convenience store coffee cup works well. coolant and water will not show on your dipstick but they will be the first things out when you pull the drain plug. oil and coolant are also the first things that the oil pump picks up when you start your engine

I drained oil into a clear container and there was no water or brown sludge in it.

In looking more closely at the "oil" and scum on the radiator cap, I think they are from the water wetter I added last year as it is clear not chocolate.

The various water wetters and "ices" all seem to be some combination of soaps and Surfactants. The soap is how they reduce surface tension to cool hot spots. And seem to clog stuff up in the bargain

Do you have an automatic? I've seen the tranny cooler fail and tranny fluid get in the coolant, much worse, water in the trans.

I am using a transmission cooler.
I am going to drain the engine/ radiator completely this weekend. The residue/junk is white and collects at the top of the radiator near the cap.

Now that you mention it, this is the other thing I noticed the one time I used Water Wetter. Made the antifreeze look "dirty" and contaminated...and oily.

Regardless of how many people on the old interweb seem to like and promote it, the product flat-out does not impress me and I will never use it again...

At the risk of being semi off topic....

I am chasing down a faint grey mist out of the left (driver's side) exhaust with regular condensation out of that side only.

Pulled the plugs on that side... front plug looks good grey/beige coating on electrode.... other three are black/sooty.

Checked the radiator, only slight scale in the overflow tank.

Emptied some oil as Neill suggested above, let it sit a while to separate if required, looks fine (if not a bit blacker than I expected), no water seen.

I can never get a good indication on the dip stick... one side usually has a smear along it (starting higher than the full mark) and the other side is just a drop of oil on the tip.

I recently added half a litre of oil (Mobil F1) to see if there was any movement on the 'smear'... none... so maybe I've just overfilled and I'm burning a bit of the oil? But that doesn't explain the condensation.

Are you sure it's condensation and not simply unburned gas puddling? 3 black-sooty plugs on one side speaks of a severely rich fuel mixture, but why one looks good leads to other questions. All this looking at fluids doesn't answer many questions. If you really want to know the internal condition of an engine and pinpoint the faliures in various cylinders without a tear-down, just do proper leak-down tests and vacuum tests to answer what's really going on in there.

Thanks craze, I'll investigate further ...some more tools to buy!

As part of registering the car I had to quieten it substantially, so instead of the Magnaflow straight through mufflers it came with from the US it now has a muffler and resonator on each side... from further research (on a Mustang site) it looks like extra back pressure can cause very rich mixture so I should at least give it a tune up... I'll also pull out the other bank of plugs to see how they look.

Once I had three normal llokin plugs on one side and one that looked like it was steam cleaned, that was the one with the head gasket leak.

looking

Mechanic did a radiator pressure test and the radiator lost pressure after about 20 minutes. Started test as 16 pounds and it lost about one pound in 20 minutes

drained and flushed the cooling systems 3 times using prestone flush kit and prestone flush solution.
Each time after flushing and getting a clear flow of coolant- thin wists of a slippery grey slime appear on the top of the coolant in the radiator. This is after running around town for 30 or so minutes

I noticed on the driver side intake manifold upper edge where it meets the heads there is a trail or seam of shiny slippery liquid. it does not appear to be coming from the valve covers.

Also a thin film of oil is leaking from the lower timing chain cover passenger side. This took about two days to develop after thorougly cleaning the surface.

And other than when I got the entire enigin soaked while flushing it runs and idles fine.

Did you do a compression or leak down test?

Replaced the timing chain cover , water pump gaskets and water pump.
Also replaced water pump backing plate and backing plate sleeves.

After several purges now have no oil in coolant.