stevesx
New Member
Hi I have just got hold of a 1979 450 SL which has been garaged for 10 years. I am changing all of the fluids but not sure what coolant to use? Can anyone point me in the right direction!
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Druk
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I've always used Comma Xstream® G40® Antifreeze & Coolant Concentrate : Manufacturer Approved Antifreeze & Coolants : Products Guide : Comma Oil & Chemicals Ltd.
Mix ratio 50% water.
Mix ratio 50% water.
A thoroughly good flush would be a good place to start if it hasn't been run in all that time - I've always found Halfords two part flush effective .
Marku
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Flush the system completely and get as much residue out and then use a waterless coolant. Anti-corrosive non pressurised and higher boiling point. Supposed to have no hot spots. Said to be kinder on old engines and aluminium. Just finishing a rebuild on my M117 450 and intend to use a waterless coolant particularly because of the non-pressurised system as have had problems with leaks before. Have replaced all hoses, head gaskets and skimmed heads etc. Hope I might have solved the problem as definitely do not want leaks as the downside is that this coolant is expensive!
hotrodder
Active Member
You really do not want to use a waterless coolant. Seriously DO NOT use that overpriced, nasty snake oil. The marketing stuff is the dictionary definition of utter BS that completely misses the point about why every car manufacturer in the known universe uses a water based coolant and specifically warns to not exceed more than 55 - 60% antifreeze
Glycols have about half the specific heat capacity of water. It's thermal conductivity is less than half that of water. Compared to water it's useless at removing waste heat.
Plain water obviously has several drawbacks related to freezing point and corrosion hence the usual solution of adding enough glycol to lower the freezing point and some corrosion inhibitors to get the best of both worlds
Boiling point is a red herring and one that the snake oil salesmen have latched onto. Waterpumps creat a pressure head inside the engine as they pump away while the thermostat restricts flow out. Allowing the rest of the system to build pressure raises the boiling point so a hot engine won't puke hot coolant after it's switched off
If an engine gets hot enough to boil the usual 50% coolant mix something is wrong. Stupidly expensive waterless coolant doesn't fix the problem it just masks it while at the same time further reducing the efficiency of the cooling system
Look up the msds for Evans npg+ and you'll find that it's at least 67% ethylene glycol and also contains propylene glycol. It's basically neat glycols + a corrosion inhibitor and priced as though it was gold. Look in the back of an MB owners handbook and it'll state that antifreeze concentration must never exceed 55% because doing so reduces heat transfer
If the stuff was any good why did Cosworth use nothing but plain water + a corrosion inhibitor in their F1 engines? Inside an F1 Engine - Racecar Engineering
Genuine MB coolant used to be based around Glysantin G05, these days it's G48 for older stuff and/or G40 for newer stuff? G48 is a HOAT coolant with silicates, G40 is a Si-OAT coolant with a slightly longer service life... 5 years vs 3 according to BASF iirc whereas MB used to recommend chagning every 2 years and now that everything is about renting cars/selling finance instead of producing well engineered cars it's 10 or 15 years [/tongue in cheek] All three flavours are available from Comma and various other brands, mix with deionised water (moreso if in a hard water area) and change according to the coolant manufacturers schedule or the origional MB schedule as the long life stuff is more about appealing to renters that bought a service plan
Glycols have about half the specific heat capacity of water. It's thermal conductivity is less than half that of water. Compared to water it's useless at removing waste heat.
Plain water obviously has several drawbacks related to freezing point and corrosion hence the usual solution of adding enough glycol to lower the freezing point and some corrosion inhibitors to get the best of both worlds
Boiling point is a red herring and one that the snake oil salesmen have latched onto. Waterpumps creat a pressure head inside the engine as they pump away while the thermostat restricts flow out. Allowing the rest of the system to build pressure raises the boiling point so a hot engine won't puke hot coolant after it's switched off
If an engine gets hot enough to boil the usual 50% coolant mix something is wrong. Stupidly expensive waterless coolant doesn't fix the problem it just masks it while at the same time further reducing the efficiency of the cooling system
Look up the msds for Evans npg+ and you'll find that it's at least 67% ethylene glycol and also contains propylene glycol. It's basically neat glycols + a corrosion inhibitor and priced as though it was gold. Look in the back of an MB owners handbook and it'll state that antifreeze concentration must never exceed 55% because doing so reduces heat transfer
If the stuff was any good why did Cosworth use nothing but plain water + a corrosion inhibitor in their F1 engines? Inside an F1 Engine - Racecar Engineering
Genuine MB coolant used to be based around Glysantin G05, these days it's G48 for older stuff and/or G40 for newer stuff? G48 is a HOAT coolant with silicates, G40 is a Si-OAT coolant with a slightly longer service life... 5 years vs 3 according to BASF iirc whereas MB used to recommend chagning every 2 years and now that everything is about renting cars/selling finance instead of producing well engineered cars it's 10 or 15 years [/tongue in cheek] All three flavours are available from Comma and various other brands, mix with deionised water (moreso if in a hard water area) and change according to the coolant manufacturers schedule or the origional MB schedule as the long life stuff is more about appealing to renters that bought a service plan
Marku
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I take it that is a no then?
hotrodder
Active Member
I certainly wouldn't, not even if i was bribed with lots of money to try it. The non pressurised thing is a bit more snake oil too... pretty much everything expands with heat and contracts as it cools down including the blend of glycols waterless coolant is composed of. Actually glycols expand more than water iirc...
While it won't boil until well after the engine has seized (cylinder head and/or oil temps) through overheating it'll still expand as it gets hot and after banging on about the lack of pressure Evans themselves still recommend the use of a pressure cap, presumably to stop a hot engne from puking the overpriced treacle out of the overflow
The only thing about the stuff that's good is the marketing
While it won't boil until well after the engine has seized (cylinder head and/or oil temps) through overheating it'll still expand as it gets hot and after banging on about the lack of pressure Evans themselves still recommend the use of a pressure cap, presumably to stop a hot engne from puking the overpriced treacle out of the overflow
The only thing about the stuff that's good is the marketing
Marku
Active Member
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Who would have thought that waterless coolant would generate so much passion. Lots of people do use it. Honda and Noble use it. Sure if you have an over heating problem it is not going to help but then you should fix it not drive around ignoring the temperature gauge. Why I am going to use it and recommend that stevesx does is because engines like ours are going to spend most of their time sitting. Anti-freeze is corrosive over time particularly of aluminium. The waterless coolant is a one time filling. It doesn't need draining and re-filling like anti-freeze so the cost is recovered. Any way Jay Leno uses it in all his collector cars after the aluminium plates on the block of a Duesenberg rotted right through.
grober
MB Master
FROM AN ONLINE source which I can't vouch for but sounds useful?
What are the different types of coolant? There are three main types of coolant categories. Traditional glycol based Green and Yellow. OAT or Organic Acid Technology and HOAT (Hybrid Organic Acid Technology). The differences are the ingredients in each category and the length of time it can remain in the system before a change. Regardless of advice, It is important to always read your original owners manual on what coolant to use.
COOLANT FOR AN EARLY MODEL 450SL MERCEDES
In the days of old however, in the case of the 1975 450SL Mercedes with a copper core radiator, the traditional green or newer yellow coolant, is the best. The green/yellow coolant MUST be changed every 2-3 years or 35,000 miles, due to its chemical breakdown. This breakdown reduces the effectiveness in keeping your cooling system from corrosion. If however you have a newer replacement radiator with a plastic expansion tank and aluminum core on your early model 450SL, you can use an OAT or HOAT (Mercedes-Benz Blue coolant). OAT and HOAT however in copper/brass core systems, do not provide the necessary corrosion protection for “yellow metals” according to Performance Radiator. and other companies I have dealt with in the past. on other classics copper or brass core radiators.
A CLEAN SYSTEM
As critical as it is to have the proper coolant, so it is to have a clean cooling system. Before you opt to simply change your coolant, you should make sure your system is scale and rust free. Even if your coolant looks clean, mineral deposits from years of water sitting or the use of tap water, will eventually reduce the effectiveness of your engine to cool and reduce the warmth of your heat in winter. The best cooling system flush chemical I have found, is the Mercedes-Benz citrus acid flush (powder) MB No. 000989102511. It is pre-measured and easily added. It is also good idea, if your radiator is original, to have the radiator inspected and cleaned by a quality radiator shop.
What are the different types of coolant? There are three main types of coolant categories. Traditional glycol based Green and Yellow. OAT or Organic Acid Technology and HOAT (Hybrid Organic Acid Technology). The differences are the ingredients in each category and the length of time it can remain in the system before a change. Regardless of advice, It is important to always read your original owners manual on what coolant to use.
COOLANT FOR AN EARLY MODEL 450SL MERCEDES
In the days of old however, in the case of the 1975 450SL Mercedes with a copper core radiator, the traditional green or newer yellow coolant, is the best. The green/yellow coolant MUST be changed every 2-3 years or 35,000 miles, due to its chemical breakdown. This breakdown reduces the effectiveness in keeping your cooling system from corrosion. If however you have a newer replacement radiator with a plastic expansion tank and aluminum core on your early model 450SL, you can use an OAT or HOAT (Mercedes-Benz Blue coolant). OAT and HOAT however in copper/brass core systems, do not provide the necessary corrosion protection for “yellow metals” according to Performance Radiator. and other companies I have dealt with in the past. on other classics copper or brass core radiators.
A CLEAN SYSTEM
As critical as it is to have the proper coolant, so it is to have a clean cooling system. Before you opt to simply change your coolant, you should make sure your system is scale and rust free. Even if your coolant looks clean, mineral deposits from years of water sitting or the use of tap water, will eventually reduce the effectiveness of your engine to cool and reduce the warmth of your heat in winter. The best cooling system flush chemical I have found, is the Mercedes-Benz citrus acid flush (powder) MB No. 000989102511. It is pre-measured and easily added. It is also good idea, if your radiator is original, to have the radiator inspected and cleaned by a quality radiator shop.
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