Bought my 2010 back in april of this year. Drove it off the lot and noticed the coolant needle was going down and back up to normal(i did notify the dealer and they are working with me). I thought air was in the system so i burped it. Problem went away for a while (maybe a month) and started happening again. Took it to subaru 3 times and they cant reproduce the issue. Finally it has started doing it very frequently and took to back for them to look at monday. Again the car warms up fine and during driving it drops one to two notches towards 'C' and does not over heat. Noticed today my coolant was on the "Low" mark..i check it frequently and this is new. Also not loosing oil as of now. When the temp drops the car kind of shudders and the temp rises again. Idk what it could be. Any ideas? Like i said i biught the car like that with 42k miles STOCK. I can see the temp on my AP drop when the needle drops as well.l, goes from about 181 to 155. Currently has SPT catback and TP tune. Unmarried AP for warranty work. Thanks and sorry for the long post. By the way, no CELs.
Got it back today from dealer-
"Could not reproduce problem, topped of coolant"