coolant temp goes down as turbo boost goes up
 

for a couple days now my coolant gauge would go from the middle to the left "C" after the turbo starts kickin in. When I slow down it goes back to normal.

this never happened before. the only thing i have changed was when I added synthetic oil to the engine. cause i never had the time to properly change the oil, ive added 2L of synthetic oil to the low oil level to give me a weeks time so i can change the oil properly.

but i doubt this oil has anything to do with the coolant temp.

any ideas?

thats pretty strange, is the turbo water cooled?

I have noticed that when the car is under load (WOT) that even though the engine temp is going up the gauge reads normal but as soon as you let off the temp gauge will spike up hotter.

Are you talking about the stock temp gauge, or an aftermarket unit?

Also, did you add the synthetic oil to regular dino oil in the car?

I dont believe the turbo is water cooled. The temp gauge is the stock gauge. The only aftermarket gauges I have is the exhaust temp, and trubo boost (which doesnt go over 5psi).

the synthetic oil i added was on top of the synthetic oil that the shop put in when they installed the turbo. I might take it down to them and have it check out this weekend

That is the Greddy temp sensor dongle doing its thing.
As to why you never noticed it before, I don't have an answer.

This is an electronic trick the Greddy kit uses to force open-loop from 1500 to 5200 RPM.

^ is it something i should be worried about?

Nope.