Coolant flush/change

capt_slow

Veteran Member
Joined
Apr 24, 2011
Location
SoCal
TDI
2015 GSW TDI SEL
I bought a couple PH test strips to test the acidity of the coolant in my other car. Then decided to test the coolant in my GSW, factory fill with about 5 years and 32K:

Fresh coolant from the bottle (left), coolant from expansion tank (center and right)


The test strips says my coolant is starting to become acidic, but I'm not sure how reliable they are. The expansion tank is clear and pink, no sediment. Should I change my coolant?
 

JELLOWSUBMARINE

Veteran Member
Joined
Mar 3, 2014
Location
yes
TDI
2011 JSW 2.0tdi 6m 1983 VW p/u 1.6 IDI 5m
According to the 3 strips your readings are all over the place. I've always stayed 7.0 or higher on coolant. I didn't even know there was a brake fluid test. According to your 3 pictures its good?
 

capt_slow

Veteran Member
Joined
Apr 24, 2011
Location
SoCal
TDI
2015 GSW TDI SEL
According to the 3 strips your readings are all over the place. I've always stayed 7.0 or higher on coolant. I didn't even know there was a brake fluid test. According to your 3 pictures its good?
I took three tests in that photo. Left strip is a control test using fresh VW-branded 50/50 G13 from the bottle. The center and right strips were taken from the car's expansion tank. There's a bit of glare on the center and right strips in that photo, but they are actually the same color.
 

JELLOWSUBMARINE

Veteran Member
Joined
Mar 3, 2014
Location
yes
TDI
2011 JSW 2.0tdi 6m 1983 VW p/u 1.6 IDI 5m
I took three tests in that photo. Left strip is a control test using fresh VW-branded 50/50 G13 from the bottle. The center and right strips were taken from the car's expansion tank. There's a bit of glare on the center and right strips in that photo, but they are actually the same color.
ahh that makes sense. Seems like your JUST on the edge. The 1st time I did the PH test I found out (like this kits directions properly say :confused:) that holding the strip in does NOT make the test better.
 

capt_slow

Veteran Member
Joined
Apr 24, 2011
Location
SoCal
TDI
2015 GSW TDI SEL
I decided against flushing the coolant. The expansion tank was clean and the job was pricey, but most importantly the actual pH of the coolant wasnt acidic yet. I guess I'll keep and eye on it.

Control test, fresh G13 50/50 mix from the bottle. PH 8.86


5 year-old, 32K mile coolant from expansion tank. PH 7.81
 

ticaf

Veteran Member
Joined
Nov 15, 2018
Location
baltimore, MD
TDI
2015 Golf SW S Manual TDI
You have already spent time and money on this, you might as well go a little bit further.
Do a partial drain, easy disconnect of the radiator hose. Refill. Still better than nothing. Do it yearly.

I'm curious, how much they charge for a coolant flush?
 

capt_slow

Veteran Member
Joined
Apr 24, 2011
Location
SoCal
TDI
2015 GSW TDI SEL
You have already spent time and money on this, you might as well go a little bit further.
Do a partial drain, easy disconnect of the radiator hose. Refill. Still better than nothing. Do it yearly.

I'm curious, how much they charge for a coolant flush?
I actually enjoyed this experiment and learned a bit from it. I had a small amount of G13 left in my spare bottle, so I ended up draining what was in the expansion tank and refilled it with what I had left in the bottle. Figured I'd try to raise the PH a bit.

Turned out my bottle wasn't 50/50, but fully concentrated. If fully concentrated G13 has a PH of 8.86, then PH of 7.81 for a 5 year-old 50/50 dilution aint that bad. Even Pentosin says G13 has a PH in the 8s.

Both dealers and reputable indy shops charge between $180-$250 for a coolant flush. Includes flushing with cleaning agent.
 

AGOODHI

Veteran Member
Joined
Jul 30, 2011
Location
NorCal
TDI
MKVII GSW, MKVI Golf
Cool experiment! I don't want to use my pH meter that I use for brewing beer :LOL:
 
Top