Question about coolant temp in winter

Hi guys!

I owned a 2012 Passat tdi 6speed manual transmission prior to my 2013 Passat DSG.

I live in Montreal and its winter here. 10F outside and 0F during the night.

As far as I remember, I dont recall my 2012 doing this.

On my 2013, when the coolant temp gauge starts to rise, if I let go of the accelerator, the needle would stop rising and if I hit a red light, it will starts dropping a bit. If the needle hits the 90C mark and I'm on the highway, everything is fine but if I'm stuck in traffic or stopped for 5-10 minutes, the needle will start to drop about 1/8th (second mark) below the middle (90C) and stays there.

Is it normal? My 2012 never did that. Is there a difference in the cooling system between a manual transmission versus a DSG?

The dealer changed the coolant telling me it wasn't right the first time but still does the same thing.

Thanks a lot.

-Mark.

Normal on my '13 in those temps.

Mine will do that...

Normal. If you don't like it get a winter front http://idparts.com/catalog/product_info.php?products_id=3931

I'm making the same observation. The heater will pull more heat out of the coolant than the engine can produce at idle and light loads. Completely normal for such an efficient combustion process.

Our ALH does this, too.

Yes, I watched my guage do exactly this today. It was only about 5 F when I went to work. Watching my coolant temps with Torque pro, it took nearly 30 minutes before my coolant hit 150F. If I was driving at 40mph, it would approach 170 degrees, but when I got stuck at a traffic light it would drop back down to like 158F and my needle would go down. Then, the light would turn green, I would accelerate and the coolant temp would rise. After driving for nearly an hour, at an average speed of only 22mph, my coolant temp was only like 175.

Thanks guys for all your observations! Searching through the internet I found this TSB from Audi that explained this situation and is categorized as normal but wondering why my 2012 temperature gauge never moves from 90° C:

Technical product information
Engine temperature display fluctuates between 50° and 90° C - all TDI
Customer statement / workshop findings
At outside temperatures under 5°C the engine temperature fluctuates according to the display in the dash insert between 50 and 70°C or till the coolant temperature reaches 90°C. The phenomenon occurs mainly when driving at low engine speed.
Technical background
Because of a very good effectiveness of the engine in low rev range, little engine heat is passed on to the coolant. At low outside temperatures the coolant temperature does not reach 90°C. If the heating is used, the coolant loses further heat depending on the blower level. As a result, the coolant temperature can fluctuate between 50° and 90° C.
Below an outside temperature of 5° C and a coolant temperature of 70° C the standard PTC auxiliary heater is activated, to heat the interior.
Measure
Please do not repair, this is normal.
Customer information
A low coolant temperature has no effect on the service life of the engine. An engine oil with suitable viscosity is used.

Thanks for posting that.