this coolant any good?
 

I have been good about using Mercedes brand coolant for the om603.

The only other consideration was Getex G5 or something like that, when I was last looking.

But it's been a few years, and I see this on the market, an aftermarket (Canadian Tire selling "OEM Premium") brand that is advertising car-specific applications.

This is what they have to say:

Designed for use in specific vehicle-makes
Recommended for BMW, Jaguar, Mercedes-Benz, Mini, Smart and Volvo vehicles
Low silicate OAT formulation
Nitrite, amine and phosphate free
Recommended change interval: Up to 250,000 km or 5 years service protection
50/50 pre-mixed, ready-to-use coolant
May also be used in gasoline or diesel engines




They also have this diesel specific kind but does not list any brands of engines:

Low silicate, phosphate and amine free
Performance rated at 6 years or 960,000 km
For use in light- and heavy-duty diesel applications where an extended service interval is required
For all on-road trucks, marine and industrial stationary and mobile farm equipment
Meets performance specifications of ASTM D-3306, D6210, JIS K-2234 and TMC RP 329


What's the current thinking on coolant religion?

Any opinions on whether either of these are OK for my om603?

And what is "low silicate OAT" anyway? I guess I'll google that.

I would be looking for the phrase "meets MB 325.0". That ensures you are giving the engine what it needs.

Zerex G05 can be found online and on sale at most of the big name auto parts stores.
The genuine MB part number is BQ 1 03 0002.

Here is the Zerex G-05 Spec sheet:
http://content.valvoline.com/pdf/zerex_g05.pdf

None of the specifications match the Zerex-G-05; however, that does not necessarily mean it is unsuitable for an 87 300D.

I would wait for more knowledgeable feedback.

A 617 would probably tolerate just about anything, but in an engine with aluminum head, to go with all the aluminum bits in the cooling system, I wouldn't deviate from MBZ approvals.

Zerex, yes, thanks, that's the name.

Zerex PDF is right up front and "proud"? to says this, "Zerex G 05 is a nitrite containing coolant designed to protect diesel engine cylinder liners from cavitation"

Whereas the aftermarket brand claiming Mercedes and diesel compatibility, description I posted says this: Nitrite, amine and phosphate free

So that's an imbalance right there.

And the aftermarket brand claiming just diesel specific compatibility, does not say nitrite free. Soo... of the two that one is sounding maybe more applicable. I just wish I knew if any of these specs "ASTM D-3306, D6210, JIS K-2234 and TMC RP 329" came close to the MB 325.0 as you have pointed out (thank you!).

Pretty sure you need nitrites for a diesel engine to prevent cavitation damage.

A very accurate point indeed. The 617 is entirely built with copper, cast iron and some rubber/plastic in regards to cooling components.

om603... aluminum head

less tolerant

I know when I was shopping around to acquire more 87 300D as a runner or for engine parts, I'd do a quick coolant inspection. If I saw GREEN liquid in there, ask the previous owner 'what kind of coolant you using'... and got a shrug or a 'Prestone'... I'd walk away from the deal

zerex G05 is probably your safest bet, or if you want to go all the way to the top then buy a gallon of final charge truck coolant, It will be fill for life in your case.

What is / where do I get "final charge truck coolant" ?

The Mercedes coolant is not OAT, but HOAT (Hybrid Organic ...). Not the same.

As far as nitrites (SCAs) to prevent cavitation damage, this is true for all engines, Mercedes makes a point of it in their literature showing the damage to a water pump impeller from cavitation. In the block however, this is more of a concern with wet-sleeve diesel engines where cavitation pitting will create holes through to the combustion chamber, in these Mercedes dry-sleeve engines it is not a risk to the block and sleeves.

So, ... I prefer Mercedes coolant or ZEREX G-05, in all of my Mercedes cars, replace regularly unless you have purchased a newer coolant tank with the SCA block in the bottom (or test your coolant annually as I do and top-up your SCAs as needed).

I would not run away from a green-coolant Mercedes, it is a small oversight if a car is otherwise well maintained IMO.

In my parts its sold at Walmart and NAPA. slightly pricey than regular stuff though. Its made by Old World Industries and its brand is "PEAK"

usual GM diesel truck buyers (lots upon lots of them in Texas), the first thing they do after taking delivery from the dealer is to flush the transmission of Dex VI and fill with Transynd ATF and then flush the cooling system of dexcool and fill with Final charge.

I use Evans Waterless Coolant in both my 300D's, just because I abhor corrosion. But, recently removed it in my 1985 while chasing a strange apparent overheating issue all last winter. Usually ran ~100C, creeping up at long red lights, and IR gun confirmed. Unlikely it is due to Evans since I ran at least one summer with it. Changing water pump, T-stat (again), etc. Hope not a crack in the head, and if it is unlikely would be due to Evans. My 1984 runs a stable 82 C even on the hottest days and use Evans in my 2002 T&C minivan.

I buy truck coolant (different than Mercedes) at my CAT dealer for my CAT engine, have used Detroit Diesel for my DD engines, put the pre-charged stuff from Tractor Supply in my loader, each has its specific needs. For older stuff the Penray SCA from my local fleet supply has worked well to top up SCAs annually as indicated by the test-strips.

I would not consider any truck coolant (PEAK or otherwise) to be "fill for life", especially if it does not have Mercedes' approval.