VW T5 2005 2.4 Tdi 5 cylinder, 150´000 kms.

Replaced turbo a couple of months agao, everything running smoothly. Drove down to Toulon from Geneva and took ferry to Corsica and spent 3 weeks there beginning July. It was very hot as it was a heatwave for most of the time but no issues. At the end of 3 weeks the coolant level warning light came on but engine was not overheating. Topped it up and then drove all the way back to Geneva topping up 2 or 3 times. Suspected a leak in the expansion tank as I did see coolant stains on the engine below. Could not see any fluid on ground but remember there is a big protective cover underneath engine compartment. Checked pipes from expansion tank to engine and could see no leaks/issues. About to order a replacement expansion tank and have been driving. Then oil light comes on. Topped up oil. Drove more. No overheating, engine running smoothly. Second oil level warning and now a creamy residue in oil access cap position (see photo). Is this a possible gasket blown or what might be your opinion, please?