I have been doing a test on K-S fluid losing its color with light exposure and here are results so far;
I obtained new fluid from both Classic and Exotic and an antique Ford source as there has been some question whether one resists sunlight damage better than the other. C&E fluid is a bit darker and more violet when fresh than the Ford.
I put samples of each in glass tubes and placed one pair behind regular convex instrument glass, another pair behind flat picture frame 99% UV blocking conservation clear glass, and another behind convex plastic UV blocking computer glasses.
So far the results are…. nil. After 2 1/2 weeks in the direct Nevada summer sun there doesn’t appear to be any degradation in any of the C&E samples, and there might be a slight turn towards amber color in the Ford samples, but hard to tell until I finish the test and compare to unexposed samples. So far there doesn’t appear to be enough degradation in anything to compare or come to any conclusions.
I am starting to wonder if the sample tubes I am using are UV blocking.
I found this site. They handle Atwater Kent sending units, plus some other interesting components. I didn’t see anything about fluid, but maybe they have some info. I know nothing about them, just passing along info.
These people have some great stuff, especially the Owen-Dyneto regulator replacement. Not a price on anything, though, anywhere.
Thanks, have heard good things about the Atwater-Kent folks. Fortunately I think I have my original sending unit sealed and functioning properly (out of the car). I cleaned up the female ends by kissing with a Dremel conical cutting bit, some polishing compound between the new conical fitting ends and added the Teflon tape. Didn’t crank the fittings down too hard and now have the loss in reading down to 1 gallon in three weeks.
I like to make the originals work when possible, even if they don’t look factory fresh.
A very curious result in my K-S gas gauge UV exposure test. The fluid in my restored gauge suddenly turned to pale brown in the period of about one week after being in the gauge for a little over two months. That gauge has been protected in the garage without direct sunlight the entire time.
Meanwhile, the two UV test fluids sat in the direct sunlight for over a month with no obvious discoloration.
The fluid in the gauge that turned was probably about 20 years old stored away in a box inside its black light blocking sleeve until I pulled it out in July.
The fluid out in the exposure test was bought new in August.
One of the surprising things was how suddenly the color changed.
Perhaps age somehow plays a role?
Interesting, I too have old fluid in my car and extra stored away.
The seven year old fluid in my car went from halfway between your July and September photographs (medium red) to your September color in about four hours of direct light exposure.
When I replace the fluid in the spring, I will buy new Classic and Exotic fluid.
Please keep us posted on any other changes or surprises you see and thank you for running the experiment.