Coolant expansion tank cap removal - how to?

[s4macs]

I have followed the owner's manual instruction on how to remove the coolant expansion tank cap to no success. Says to depress the slide mechanism on the cap, turn to the left, and then when resistance is felt, depress the slide on the cap again and remove the cap. I have tried this in all locations - meaning trying to depress and remove as I rotate it to the left and in no position will it remove. I just received a coolant level warning light after a cold start. Any thoughts? Thank you.

[AldermanToffee]

Yes, that’s correct. Which part are you struggling with exactly just to clarify?

Press the locking “tab” inwards towards the centre of the cap and rotate it anti-clockwise. It does take a few spins to get it all the way off.

If it’s not spinning just use more force, it’s probably on quite tight.

[s4macs]

Thank you. Seems you are saying that it will require at least a few complete rotations of the cap? The instructions say to rotate it until resistance is felt (which I've done and pressing in the locking tab), but it reaches a point of not wanting to unscrew any further. even before a complete rotation..did not want to force it.

[s4macs]

OK - all good...just kept turning past the resistance I was feeling and it did unscrew. Now need to figure out the proper coolant 'color'. I have PORSCHE pink on hand, but not much else :)

[AldermanToffee]

OK - all good...just kept turning past the resistance I was feeling and it did unscrew. Now need to figure out the proper coolant 'color'. I have PORSCHE pink on hand, but not much else :)

G13. Nice and pink. Or G40. Porsche stuff will work fine.

[Smac770]

The car should have a label marking if it's G13 or G12evo.

Profile says 2013 S4, this is the B9 S4 forum though. What's the actual year S4 in question here?

According to the TSB, MY19+ used G12evo. https://static.nhtsa.gov/odi/tsbs/20...76873-0001.pdf

[s4macs]

The car should have a label marking if it's G13 or G12evo.

Profile says 2013 S4, this is the B9 S4 forum though. What's the actual year S4 in question here?

According to the TSB, MY19+ used G12evo. https://static.nhtsa.gov/odi/tsbs/20...76873-0001.pdf

Yes....profile not updated. I have had a 2013, 2016 and now 2019. Anxious for Audi to do a refresh (not just gingerbread adds) so I can buy another...just love the S4 as a daily driver.

[s4macs]

G13. Nice and pink. Or G40. Porsche stuff will work fine.

My Porsche coolant says it is G30-91...only needed to add about 8 oz (50/50 mix) for the warning light to go away. Will check with Audi tomorrow to get their thoughts as well on compatibiity. Thank you all for your prompt and helpful replies.

[SHCKR]

OK - all good...just kept turning past the resistance I was feeling and it did unscrew. Now need to figure out the proper coolant 'color'. I have PORSCHE pink on hand, but not much else :)

This stuff

[AldermanToffee]

My Porsche coolant says it is G30-91...only needed to add about 8 oz (50/50 mix) for the warning light to go away. Will check with Audi tomorrow to get their thoughts as well on compatibiity. Thank you all for your prompt and helpful replies.

That’ll be fine. General rule of thumb is that if it’s the same colour, it’s compatible.

[Smac770]

As the linked TSB points out, there's compatible and then there's optimal compatible. If using G12evo, you should try and limit to using just G12evo. If using G13, then either G13 or G12evo is sufficient. G13 was replaced with G12evo for latest heater core welding or composition compatibility is what one member pointed out some time back.

Porsche G30-91 seems to be a G12 equivalent (G12+ maybe). What's the actual Porsche part number on the bottle?

[Smac770]

Went looking into the Porsche stuff some more.

VW standard	VAG term	BASF term	composition	comments
VW TL 774 C	G11	G48	glycol + Si IAT	blue-green
VW TL 774 D	G12		glycol + OAT	red; not G11 compatible
VW TL 774 F	G12+	G30	glycol + OAT	pink; reformulated to be G11 compatible
VW TL 774 G	G12++	G40	glycol + Si HOAT	pink
VW TL 774 J	G13		glycerin + Si HOAT	violet
VW TL 774 L	G12evo	G65	glycol + PSi HOAT	violet

If we look at the history of the Porsche 1G premixed coolant for US market starting with the first joint Porsche/Audi model, 2004 Cayenne:
000 043 300 88 - G30? can't find a decent pic of this bottle on the Internet
000 043 301 05 - G30-91 EF
000 043 301 49 - G40-91 EF
000 043 305 75 - G40-91 EF

Oddly, the 1L concentrate bottles appear to have no specification marked on them. Though it's simple enough to align the dates.
000 043 203 78 - G30, 2004 Cayenne started with this, dropped Jul '06
000 043 301 03 - G30, 2010 Panamera started with this, dropped Sep '13
000 043 301 47 - G40, 2014 Macan started with this, dropped Sep '17
000 043 305 15 - G40, used till Aug '21 for new build
000 043 304 73 - G65, used since Aug '21 for new build

For topping off, G30 won't create problems. But if your vehicle uses G12evo, as Audi seems to imply MY19+ do, you really should get a bottle and have it around.

I have to assume G13 glycerin, marketed as more carbon neutral, was really about costs; I mean, we're talking about VAG here. And Porsche skipped it.