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Purchased some DOT4 clutch/brake fluid last summer and performed the Ranger method fluid change a couple of times. It has been stored with the cap tight and in a zip lock bag. I have seen many comments about the fluid being hydroscopic, thus any concerns using the remaining fluid to flush again?
Also, any thoughts on synthetic vs non-synthetic fluid?
It is hard to say about the stuff in the zip lock bags. Some bags may not be an effective moisture barrier. They may slow it down but not prevent it. Others may be true moisture barriers. The only way to know is to try it. At least it isn't a safety issue like the brakes are.
I put my opened containers in a zip lock bag but if they have been in the bag for more than two months I don't use them.
There are some fairly inexpensive electronic brake fluid testers out in the market( I got mine from Amazon). I tested my Dot 4 I had sitting about for about a year, it registered it had about 8% moisture, but when I tested my clutch fluid, the moisture reading went off the scale. I would buy a tester to test your fluids you have had sitting around a while just to be sure. You would also be surprised to see how much moisture is n your brake master cylinder fluid. Brake fluid needs to be changed a well
A fresh bottle of brake fluid isn't that much. Why spend $$ on a moisture tester that won't be periodically calibrated? Unless, of course, you just want more toys and gadgets.
A fresh bottle of brake fluid isn't that much. Why spend $$ on a moisture tester that won't be periodically calibrated? Unless, of course, you just want more toys and gadgets.
Ron
I would toss it! I only buy enough to use for the Ranger method and toss what is left.
In my former life we tested many ways to package welding wire. The worse was a sealed plastic bag! Thin plastic is permeable and water vapor (and other gasses) pass through it, albeit slowly. If it's a plastic container it will take longer because it is thicker. A metal can was used for the most expensive 140,000 yield strength welding wire used to fabricate some small mini submarines, etc. Best for others was what is called vapor-paper that is chemically coated.
Yeah, I just did it a few weeks ago and have waaay to much left over (I got the mega size bottle) but I am scared to re-use so I hear ya. I have the garbage GM flywheel issue with hot spots I have been fighting GM about, so I will be doing a clutch package soon anyway but it DID improve my shudder at low speed doing the ranger method.
May be okay; but I give up, why not just use new to be sure? It isn't like it's going to cost an arm-&-leg to do so. Maybe in a junker to sell, but... come on.
There are some fairly inexpensive electronic brake fluid testers out in the market( I got mine from Amazon). I tested my Dot 4 I had sitting about for about a year, it registered it had about 8% moisture, but when I tested my clutch fluid, the moisture reading went off the scale. I would buy a tester to test your fluids you have had sitting around a while just to be sure. You would also be surprised to see how much moisture is n your brake master cylinder fluid. Brake fluid needs to be changed a well
For fun, checked out the product and price on Amazon. Then put the product name in Google (as I do periodically.) The price directly from China is ~$3 on eBay and even less from some other sources I would not trust to buy from! Since I am within a few months of my annual Ranger method -bought one! Should arrive by then.
It appears to be a resistivity measure with two probes. Readout is several colored LEDs. Easy thing to check as I will have old fluid and new from a just opened container. Will also leave some of the old fluid exposed and check all measurements with a quality digital VOM! Reminded of the simple meters used to measure wood moisture.
Also how can it be possible to make, sell and ship for $3?
Most quality brake fluids are synthetic and similar Glycol-ether based. Replacement of the reservoir contents ~6 times in the Ranger method once per year (which I have been doing before my C6) should be good enough. May not be quite as good as a bleeding from the slave cylinder every 3 years as recommended in the Owner's Manual but is much easier and has worked for me and many others.
Just checked and have a few ounces of brake fluid left in 12 oz cans from Prestone and Valvoline in my Ranger kit. I trust the brands, the SAE specs they say they meet and Walmart turns inventory very quickly! I'll check those two old containers with the test mentioned above (not sure why I didn't throw them out as I would never use them!) As some have mentioned, it's too cheap and a 12 oz container will be mostly used with the Ranger method!
For those who have not used the Ranger method, pics below are the results from the first Ranger flush I did after a year in my 2014 C7. With 30 pumps of the clutch after each empty/refill of the reservoir, it shows, IMO the fluid does mix with the slave cylinder. GM says the dark color partly comes from the throwout bearing seals, which is no doubt true. The Ranger method appears to replace most of the old fluid.
And all you are doing is changing the fluid in the reservoir. Not the master cylinder, not the line, not the slave. But the reservoir does have clean fluid.
And all you are doing is changing the fluid in the reservoir. Not the master cylinder, not the line, not the slave. But the reservoir does have clean fluid.
I don't agree and if you search the Ranger info, Video and data you'll see it's more than that!
Look at my post #15. That 30 pumps per replacement in the reservoir does more than just empty fill it with new fluid. Fluid does mix in the master cylinder or it would not get progressively cleaner after 6 dump/replace cycles. May not get a high percentage of the slave cylinder although again look at the Ranger info and he shows it does!
He is a drag racer where there is a lot of clutch material entering past the slave cylinder seals. He finds the method works for him as do many of us! Understand your argument, it has been raised before and the answer may fall between your-no mixing and Ranger mostly mixed!
IMO a once a year Ranger use is as good as an every 3 years (as recommended in the Owner's Manual) bleeding from the slave cylinder. However that requires removing the drivers' side Catalytic converter and exhaust pipe and some of the sheet metal covering the exhaust pipe. Then bleeding from the slave cylinder fitting. A PIA and >$150 dealer cost assuming they do a good job!
Don't expect you to change your mind as it is obviously made up but perhaps these comments will help the ~500 silent majority who have viewed this thread versus the ~10 of us who have posted! Been only using the Ranger method at oil change time since I got my 2008 Z51 C6, then my 2014 Z51 and will my Grand Sport soon, as the oil change is coming up! Never had a clutch problem!
And all you are doing is changing the fluid in the reservoir. Not the master cylinder, not the line, not the slave. But the reservoir does have clean fluid.
Then why when you suck out all of the fluid in the reservoir and put in fresh, does it turn dark when you pump the pedal? Must be cycling the dirty oil from the line.
03-05-2018, 12:39 PM
Clutch fluid still good?
I would toss it! I only buy enough to use for the Ranger method and toss what is left.
Been only using the Ranger method at oil change time since I got my 2008 Z51 C6, then my 2014 Z51 and will my Grand Sport soon, as the oil change is coming up! Never had a clutch problem! 
