Thermostat Replacement and Correct Coolant

[ericycle]

Hi guys,

I intend to replace the thermostat on my 2006 W203 C200 CDI (OM646) this weekend.

The coolant currently in the system is G13 (see attached img). It was used after replacing the water pump a year and a half ago by a mechanic very familiar with these cars (used to work in a MB dealership for many years).

When replacing the thermostat, I will have to add some coolant, so I was looking to buy more coolant. I'm assuming that mixing different types of coolant is a bad idea. So I was looking for the same thing.

At the parts store the guy said Valvoline MaxLife is compatible with G13. Its PI sheet says "MB 235.0,2,3, 5" and "VW G11, G12+, G12++ and G13 applications" among other things.

My first question is, does this mean I can safely add some Valvoline MaxLife to the existing coolant (mix with the existing G13)?

 

[brucemillar]

On a personal preference !! I would flush the whole system and start again. Get it wrong and you face a mahoosive bill.

 

[ericycle]

How do I even know what the correct coolant is?

My service booklet doesn't reference any MB spec for coolant (it does for engine oil and transmission oil, but not for coolant).

I'm familiar with the MB Specification 325.0, but there's also 325.3, and 325.6. What is the difference between them? How do I know which one I should go by?

From the 325.0 spec, I can get either Zerex G-05 or the Rowe Hightec AN.

But if the Valvoline MAX life spec is correct, and it does in fact support MB 325.0, than that should be fine. The only question is can I mix the MAX life and the G13 that's already in there?

 

[hotrodder]

For what coolant costs* i'd be inclined to do the same as Bruce. Or drain a few litres off so it can be reused instead of letting it spill when changing the 'stat

According to the internet G13 is VAGs internal designation for G40 Si-OAT so should mix happily with anything using the same Glysantin 'recipe'
MB325.0 coolant specs covers G05 and G48 which are HOAT flavours with silicates. MB325.5 is G40 / Si-OAT stuff and MB325.3 is G30 aka G12 (VAG again), an OAT flavour with no silicates

I don't really do modern cars but AFAIK mb325.0 is/was used on most (all?) passenger cars for eons and they might have switched to 325.5 G40 on later stuff for extended service intervals? That said extended service intervals are mostly about appealing to fleet buyers/renters i.e. lower service costs for the initial owner rather than long term health of the thing. Service interval for my s124 (G48 coolant) is 2 years according to MB, upto 3 years according to the people that make the coolant and for later MBs that use exactly the same flavour of coolant a LOT longer...

HOAT with silicates and Si-OAT stuff are fairly similar and Valvoline aren't cowboys so you should be fine. That said coolant colours often tend to vary a bit by brand and are fairly meaningless as it's just a dye and there are no standards about what colour different flavours should be dyed so you can get some weird/nasty colours when mixing different brands of the same flavour

* 5 litres of G48 or G40 concentrate should be around a score from a decent motor factor (i.e. not hellfrauds or eurocraparts). Buy some deionised water to mix it if you live in a hard water area/don't have a water butt with and should still be under £25 total