Using Coolant Test Strips
 

I thought I would entertain myself by testing the coolant in my three Benzes. Two of them have Zerex G05; one has Zerex G48.

The test strips I got are Fleetguard 3-way test strips. They test glycol/freeze point, molybdate, and nitrite.

I understand how to do and read the test. What I'm uncertain about is whether these test strips are a good way to test my particular (Zerex) coolant.

Maybe I'll give Valvoline tech support a call next week. But I thought I'd check with you guys to see if you have any insights.

I should probably just change the coolant on all three. But, as long as I have the tests, I might as well see what I can learn.

Let us know what you find out.

I've always used the NAPA green coolant, the NAPA test strips, and NAPACool additive to keep the nitrites up. No worries about compatibility that way, and it's cheap and it's available in my little town.

Poking my nose around a bit, it seems like I need test strips that are designed for HOAT coolants (according to Fleetguard technical support). I called Valvoline and they were no help.

Are you testing the coolant because it was contaminated or diluted sometime in the past? A good rule here is 5 years of use with G48 and G05 Zerex stuff. Just drain and replace if the liquid was a 50% mixture. The additives get depleted by then.

If the liquid was not a 50% mix, you will need to do some math to correct that mix.

Now if you were using something like a Peak's Final charge or any ELC your 5 year mark doesnt count, that coolant can work for upto 10 years in these cars. And to keep in good condition, you can buy the test strips for that specific coolant.

In the W211, interval is 15 years or 143,000 miles. But that's a long time...so I'd like to test it.

I am unable to find any test strips specifically for Zerex...Valvoline certainly doesn't sell any. But there are some that work with (H)OAT so that's probably my best bet.

Found some test strips that work with HOAT coolants.

Fleetguard CC8997. But you have to buy 25 strips and there is an expiration date.

Phoenix Systems 8001-B. You get 100 strips and apparently no expiration date.

HOWEVER it doesn't sound like there's one test strip that tells you everything you'd want to know (various inhibitors, etc.). The cost of an adequate test probably exceeds the cost of DIY changing the coolant.

Whatever you do, don't use "Extended Life" coolant, which is intended for certain GM cars. I put some once in my 1996 Plymouth after a good flush. I don't recall it said "Dexcool", probably because of a branding thing. Wags term it "Death Cool". Seems it reacts over time with leftover green coolant to form brown solids. Years later, I found such floating at the top of the radiator and eventually clogged it to run hot, which a radiator back-flush fixed. I also got a lot of rusty water from the flush, so might be "bad chemistry" (fight between acids).

That is the only car I don't now have Evans Waterless Coolant. Waterless should be good for life with no corrosion worries. You might roll-your-own by mixing pure proplyene glycol (Sierra brand) with ethylene glycol (regular green stuff). I've driven one of my 300D's up the I-5 grade at 65 mph over the Tehachapi Mountains north of L.A. on a 105 F day and the dash gage never exceeded 90 C, so good-enough (some factory designs are validated there). With no corrosion, it should never get worse. Studying all the other coolants out there today can be confusing.

The 15 year interval is only with the original expansion tank - it has a silica packet in it. Hoping no one ever added the wrong stuff in the system (like all model all makes) it will work, if the wrong type was added, the silica packet becomes useless in a short while.

Good point. Yes, on both of mine it has only ever been Zerex G05 or G48. MB's contention is that, as long as only 325.0 spec coolant is all that's ever used, the silica pack lasts indefinitely. Some on this forum have claimed that the silica pack wears out and thus, eventually, coolant should be replaced every five years or so. But I'm working under the assumption that MB is correct....even though I'll probably chicken out and replace before 15 years.