What anti-freeze?

[partsman]

I am curious about my anti-freeze, on the used 96 truck I bought I checked with a hydrometer and came up with -10°F, which is too low for my liking, and the other thing is it looks like light green or yellow in colour, is it possible they changed types?

Should I use Dex-cool, and if so do I have to run a hose to flush out the old first, then fill with new?

[leolkfrm]

No on that old of a truck stay with the green, green sounds like vavoline or napa, yellow is usually prestone. I always like to keep them lower than -20. if it looks clean drain a gallon out and put a gallon of whole antifreeze in, save the drained for adding later

[bradrhale]

must be a northern thing. it got down to 20 degrees here once. that is 20 above zero. cold night that night.

[leolkfrm]

20 thats t-shirt weather

[chengny]

It takes a lot of very cold (below -20F) days in succession (and a situation where the vehicle sees no sunlight and is not started) for the core temp of a motor to reach that point. Even then, the coolant does not "snap" freeze into solid ice, but rather turns into slush by degrees first.

And, always bear in mind that, along with the antifreezing properties that ethylene glycol does contribute, you also loose some heat transfer capacity that plain water does so well.

A 50/50 mix is the max you should ever require - and even that is too rich.

Remember, that as soon as your engine warms up, it has no idea whether it's July or January outside the engine compartment. The internal temps are just as high and all that heat needs to be picked up from the cylinder walls and heads, carried away by the coolant and then given up to atmosphere in the radiator. Water does this much more effeciently than EG.

Mix your coolant to protect down to 0 and install an in-line heater in the lower radiator hose. Then, on those few nights each winter, when you are really concerned about ice up, just plug it in. Makes for a nice easy start it he AM and the initial thermal stresses are greatly reduced.

Your motor thank you come summer when the coolant is more water than EG.

[leolkfrm]

antifreeze also raises the boiling point! stay with the -20 and be safe, it not only protects the engine but all the attached hoses and heater core.

[scavanger]

You want to stay with a 50/50 mix. That is in the area of -30 F. You have to remember if you have air cond. you need the 50/50 . If you go with a lighter mix you should ad rust inhibtor-lube to protect the cooling system.

Scav.

[chengny]

Certainly didn't mean to imply that coolant containing a reasonable amount of ethylene glycol was not a good thing. Rather, I was trying to point out that people can sometimes forget what the purpose of the coolant is. In their quest for protection against lower and lower temps, they can get to the point where all they think about is freezing point.

The primary purpose of the coolant in an engine is to remove the heat of combustion to atmosphere. And while EG can certainly lower the freezing point of the coolant, it also signifcantly impacts the specific heat capacity (i.e. the ability to transfer heat effectively) of it as well.

Only offering another example of how sometimes "more is not necessarily better".

Please look at the attached charts, they are simple, yet quite effectively demonstrate that freeze protection comes at a cost.

[leolkfrm]

I've read basically the same charts in regards to my outside boiler for the house! it is a non pressurized system, and de-oxygenate must be used! If you want to run your collant at 0 degrees so be it, however I (and speak only for myself) would never reccommend >-20 for normal use.
BWAI

[chevyguy]

As long as its well below freezing I would let it eat. No reason to raise the temp. Its not hurting anything where it is. My truck is at zero adn so is both my cars. I now live in Alabama and if it get to below zero I have a real problem.