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Old 05-12-2001, 02:15 PM
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JimF JimF is offline
'94 S500: only 793 sold!
Join Date: Mar 2001
Location: San Diego, CA
Posts: 1,924
Neat Tester!

The antifreeze/water mixture in my car was not even close to what I thought it was!!!!

The car's AF was changed at the dealer just before I bought it and I assumed (there's that word again!) it was 50/50% to start with. Bad assumption!

[my convention: xx/yy% = anti-freeze/water]

So in doing my calcs to get to 30/70 or 20/80, I removed what I thought was enough coolant. But enough to err on the conservative side. Remember this 'experiment' is to see how better it cools with Water Wetter (WW) starting from a 50/50 solution, so I thought!

Today, I picked up a AF tester made by Prestone (to make Bill Lewallen happy!) and used it to test my mixture.

WOW! Not even close. It's very close to 40/60% not 20/80%! So it MUST have been around 70/30% to start with! That was my point in one of my earlier posts. It's hard to really know unless you test it YOURSELF!

I've marked the concentration points on the picture so it's very easy to read your car's mixture ratio based on temperature in C. The RED pointer indicates the freezing point protection. Do this with a cool (cold) readiator and fill the tester to the indicated mark. The Prestone PN is AF1420P. $2.89 at AutoZone.

All this started because I want a year round mixture ratio that does not need to be changed. In San Diego, the temp averages 71 F. The coldest it gets is possibly 36 F.

We go into the mountains in the winter and it gets to no colder than -5F (-20C). So that where I'd like to set the car's mixture ratio. That works out to 40/60 ratio min! That should give adequate protection. I wonder how much cooler it would be with 20/80% and Water Wetter? Probably never know.

So even for me in SD, my original idea of 20/80% is NG and a 35/65% ratio would be probably the absolute minimum acceptable ratio. If I were to always drive in SD only, then it probably would be ok. But for the colder climates it is a disaster waiting to happen.

Even 40/60% may be very problematic for some cold northern climates.

So all previous comments reflect a 40/60% mixture with WW, not an 20/80% mixture which started from 70/30% mixture.

[Edited by JimF on 05-15-2001 at 12:49 PM]
Regards . . . . JimF
'94 S500 Cpe

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