Is this oil residue in our '15's coolant reservoir?

[ReadTheBook]

Haven't run into this on previous cars so not positive what I'm looking at and I'm hoping it's not early signs of head gasket failure. It's an early build (April 2014) '15 Golf SE Sport and has developed an oil-colored film above the coolant line.

It is also losing some coolant (again!), but I'll talk about that in the coolant thread...

Car has 54,891 miles on the clock.

The motor has typically consumed about 1/2 qt of oil every ~5k (always ~5k intervals) upon extraction, but in today's oil change and it was a good qt low. The coolant color inside the bottle still looks violet, not milky, but maybe a touch murkier than I'd think it should be.

 

[theDoktor]

Wouldn't hurt to do both a leak-down and compression test on it. You should have at least 90% or slightly more on all four cylinders when doing a leak-down test- most likely will be in the 92-94% range if everything is good. A hand-built race motor will be between 95-97% typically when fresh. More than a couple percent difference in any single cylinder would lead to more checking. If it's a head gasket going bad, you'll see air bubbles in the coolant overflow tank during the leak-down test (with the cap off). If you have air comming out the oil fill cap, the rings are not holding compression. Those of you who might not be familiar with a leak-down test, you are pressurizing each cylinder with compressed air and monitoring how much pressure is lost internally in the engine vs. the input pressure. Where the lost pressure goes tells you where compression is being lost- out the tailpipe= a bad exhaust valve; out the intake= a bad intake valve; out the oil fill cap= bad rings; bubbles in the cooling system= a head gasket leak. Improper cam timing can also be identified by doing both tests. After a warranty head gasket replacement on a previous VR-6 powered Corrado, it was noticeably down on power. Dealer claimed everything was just fine. It wasn't, so I paid them to do both a leak-down & compression test on it. Leakdown was at 95% on all 6 cylinders; compression was at 125 psi on all 6 cylinders vs. the shop manual value of 175psi. Car only had about 25,000 miles on it and was still under factory warranty. Dealer's ASI-certified lead mechanic with multiple VW Service School certificates and with over 25 years experience didn't understand the readings; I had to get the VW Zone Rep to explain to him that they mis-timed the cams when they put the head back on. The dealership refunded me for the test cost and properly timed the cams.
Compression should be at least 125psi and have a variance range of no more than 5 psi. A quick verification on a low compression reading can be made by squirting about a tablespoon or so of oil in the low cylinder & rechecking the compression. If the pressure comes up, at least briefly, the rings are going south.

 

[ReadTheBook]

I hope it’s nothing. It’d be kinda shitty if this happened to a well maintained, 10k/yr of easy driving, vehicle at 50k miles and it would perhaps spook me away from M1 as my oil.

Thanks for the response.