The thermostat raises pressure in the head, which helps keep the valves cool. Without it, you would need a restrictor. And if this is the Lotus, you would need to block the bypass. Or you could choose to believe track legend and say you need a restrictor to slow flow through the radiator (really...ask around and some duffer is sure to tell you that).

A race car is one place where you probably have to run pure water. Not for cooling reasons, but because most racing authorities won't allow glycol in track cars. The reason being that if glycol spills due to an accident or just over filling, asphalt pavement becomes extremely slippery.

I have a Zerex jug that does have a mark at 4qt - I put it there

Re the no thermostat comments. So far as I know, it is a very bad idea. MB say so! If you have no thermostat, the bypass is open so only part of coolant goes through rad. Tstat has two valves. One to close bypass and one to open flow from rad.

see Coolant flow question

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

If I run Evans waterless in the 1984 300DT, will the heater still work in the wintertime?

Why wouldn't the heater work? The coolant will still be circulating at engine temps. If your monovalve is good and the heater core isn't plugged up you should get plenty of heat. If the AUX pump still works, you should have a surplus of heat.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

I still couldnt get why the 4qt mark is needed - the jug capacity is 4 qt and no room to do any proper mixing anyway. The other component (water) is also to be measured and a qt container for it is almost commonplace everywhere.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Today, I was cleaning up the mess in my shop and had a look at the 4qt mark I had marked on a Zerex jug. It is just before the jug narrows down. It's useful to have when mixing up 50:50.

BTW, this jug stuff started as a joke and still is Sorry to have started it because this thread has some good info.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

A 50/50 mixture is used all over the mid-west. It protects to minus 34 degrees F. That is the mixture recommended by Mercedes on its one gallon anti-freeze jug. That produces a boiling point of 225 degrees at atmospheric pressure and 275 degrees with a pressure cap, according to the same jug.