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synthetic brake fluid revisited

R

rv7charlie

Well Known Member
A quick review of earlier threads seemed to indicate that Mobil 1 synthetic ATF is fine with stock o-rings, etc in the brake system. However, I couldn't determine whether it's ok to use it in an existing system that's had the old (5606?) fluid in it. Is it ok to use it, if I use the ATF to push the old fluid out of the system?

Also, when I bought the ATF ('multi car'), the bottle indicated that some post 2005 models need a different Mobil 1 synthetic ATF. Is either version ok for a/c brakes?

Thanks,

Charlie
 
Try mixing a little together on the bench and see if anything happens.
I pushed one fluid out with a different one and got glue. Had to flush for hours with several gallons of alcohol to start over........
 
Can I get it at a local auto parts house on Sunday morning?

I'm not trying to be trite or contrary; this is a serious question. For example, I know that many RVers use high dollar aviation specific starters, but I've used automotive starters for 20 years on multiple a/c & never had a problem. I paid 1/2 to 1/4 of the a/c cost, & if I'd had a problem, I'd never be stranded waiting for a Fedex shipment. Same principle applies to alternators & many other products used on our planes. If I can replace an a/c specific product with a generic, locally available replacement that meets or exceeds the requirements, I see it as a win for me, and a win for aviation in general, because it makes aviation more affordable & accessible.

FWIW,

Charlie
 
rv7charlie said:
Can I get it at a local auto parts house on Sunday morning?

I'm not trying to be trite or contrary; this is a serious question.
Click to expand...

And I'm being serious too.... when your brakes fail it will ruin alot more than your Sunday:eek:
 
I'm willing to learn; please explain why my brakes will fail from using this product, when, according to posters on this forum, many others have used the product for years with no problems.

Caution is fine; that's why I asked the questions. But unreasoned fears simply impede progress.
 
Just because someone on the internet says it's ok doesn't necessarily make it so!

And I'm not a chemist either, but it would seem to me if you start experimenting by intermixing fluids and seal materials the results are unknown (I'm also not aware of any aircraft brake manufacturer that has approved ATF as brake fluid).

Safe flying is all about minimizing risk, I'm not going to risk my aircraft or the life of myself or my passengers just to save a few $$, plain and simple.
 
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Yes

rv7charlie said:
A quick review of earlier threads seemed to indicate that Mobil 1 synthetic ATF is fine with stock o-rings, etc in the brake system. However, I couldn't determine whether it's ok to use it in an existing system that's had the old (5606?) fluid in it. Is it ok to use it, if I use the ATF to push the old fluid out of the system?

Also, when I bought the ATF ('multi car'), the bottle indicated that some post 2005 models need a different Mobil 1 synthetic ATF. Is either version ok for a/c brakes?

Thanks,

Charlie
Click to expand...

Charlie,
Yes, the Mobil 1 synthetic ATF is compatible with the Nitrile rubber components in your brake system. Both the Mobil 1 ATF and Mil-H-83232 fluids are compatible with Mil-H-5606 fluid. Be sure to thoroughly flush the system to purge it of any old fluid. The purging is done simply so that the performance of the new fluid will not be degraded by remnants of the old 5056 fluid. There are no "compatibility" issues involved.
The post 2005 Mobil 1 ATF exceeds GM's new Dexron VI specification. Both Mobil 1 ATFs meet Mil-H-83282. The original Mobil 1 ATF exceeds the requirements for Ford's Mercon V. Can you provide Mobil part numbers for the two fluids? With the part numbers, some Google research would determine if the newer fluid would have added benefits.
Charlie
PS You can further upgrade your brakes by replacing the Nitrile O-rings [250 degrees] in your calipers with 70 durometer, Viton rubber units [400 degrees] I believe that Gary Van Remortal was the first one to recommend that change. Caliper O-ring size is 2-218. You will need one O-ring for each caliper.
 
If you move away from the "STANDARD" brake fluid, it might be a good idea to note on the reservoir the type of fluid used. It will also be noted in the aircraft log book.......
 
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Hi Charlie,

I converted to the Mobil 1ATF a couple of months ago. I simply used a small pump to remove the old 5606 from the caliper up and then used the same pump to push the ATF in from the bottom. I also replaced the caliper o rings with viton. Removing the 5606 first flushes the system of all old fluid and creates an air break between the old and the new.

Cheers,

db
 
rv7charlie said:
Caution is fine; that's why I asked the questions. But unreasoned fears simply impede progress.
Click to expand...

So true. A few of us have been running DOT 5 for years and boy do some say that's a horrible, stupid thing to do..... The Ferrari doesn't have any issues either ;)
 
Two years ago when I first tried to bleed my brakes, I used some 5606 another builder had. I had a lot of problems with the bleeding process and ran out of what he gave me, and decided to go with Mobil 1. I mixed some of the two together first to see if there would be any reaction and after a week there was nothing, so I simply drained the 5606 and added the Mobile 1. Two years later (still not flying), the system remains leak-free and a recent re-bleed went fine.

So, from my limited experience, the two are compatible.
 
Many thanks to all who replied. Master cyls are now re-done, and the system drained & refilled with M-1 ATF. 1st flight (and landing/taxi) went fine.

Charlie K,

The fluid I found locally was Mobil 1 Synthetic ATF, Multi-Vehicle Formula. UPC is 71924-25201; the number next to the new 2D dot matrix code is 98JJ22. Bottle says 'recommended by ExxonMobil for use in 2005 and earlier GM vehicles. ...etc; also mentions Fords requiring MERCON V and Chrysler auto trans.

Charlie
 
Space shuttle brake fluid

Last night I was reading a book I bought at Oshkosh about the space shuttle. In the section on the braking system I came across this:

"The hydraulic fluid is a synthetic hydrocarbon to reduce the risk of fire and is to specification MIL-H-83282."

That's what we put in our RV-6A, along with the viton o-rings. If it's good enough for the shuttle it's good enough for me.

--LeRoy Johnston RV-6A "Esperanza" 496 hours Ohio
 
rv7charlie said:
A quick review of earlier threads seemed to indicate that Mobil 1 synthetic ATF is fine with stock o-rings, etc in the brake system. However, I couldn't determine whether it's ok to use it in an existing system that's had the old (5606?) fluid in it. Is it ok to use it, if I use the ATF to push the old fluid out of the system?

Also, when I bought the ATF ('multi car'), the bottle indicated that some post 2005 models need a different Mobil 1 synthetic ATF. Is either version ok for a/c brakes?

Thanks,

Charlie
Click to expand...

Charlie,
The "newer" stuff, as you call it, is NOT Mobil 1 synthetic ATF. It is Mobil Dexron VI synthetic ATF. Not the same thing. Last year, I downloaded the PDS for Mobil 1 from their site. I posted that link on a thread regarding Mobil 1 versus Mil-H-83282 last year. It seems that you can no longer access that info on the web. I saved that info, so if you want, I can email you the PSD for both the Mil-H-83782 [Royco] fluid and Mobil 1.
The short answer is that Royco Mil-H-83282 has a flash point of 445 F [229 C] Mobil 1 has a flash point of 428 F {220 C]. So the Mil stuff is slightly better, for about 4 times the price. The Mobil Dexron VI fluid has the same flash point as the Mobil 1 synthetic ATF, so there is no advantage/disadvantage there. Since there are other possible differences, best to stick with the Mobil 1, if you plan to use that, rather than Mil-H-5606 or Mil-H-83282.
Charlie Kuss
 
Better than Mobil 1 ATF

A lister from the UK RV Squadron just pointed me in the direction of another manufacturer of synthetic ATF [automatic transmission fluid]. It appears that the flash point for Amsoil Synthetic ATF is superior to Mobil 1 and slightly better than the spec for Mil-83282. Looks like those who like the Mobil 1 now have a better, low cost alternative. See

https://www.amsoil.com/storefront/atf.aspx

Charlie
 
rv7charlie said:
Can I get it at a local auto parts house on Sunday morning?

I'm not trying to be trite or contrary; this is a serious question. (snip)
FWIW,

Charlie
Click to expand...

Nope, but if you're stuck at a random airport, it's probably easier to find 5606, which is totally compatible with 83282/Royco 782. Also, if someone who doesn't know better tries to help you out they'll see red and assume it's 5606--no harm done.
 
manufacturer recommended

Of interest to note, when I first installed fluid in my brake system, I used the Mobil synthetic ATF and had some issues with getting a good bleed, even when filling from the brakes with an oil pump can. Turns out that due to my 13 year build, the seals had dried out and let in air. The manufacturer offered to install the rebuild kits for me for the same price of the parts. The rep asked what type of fluid I was using, figuring that could be the problem and when I said synthetic ATF he said that was what they recommended. The cylinders were rebuilt and the subsequent fill was simple. Been working fine for the 2 years I've been flying!
 
gasman said:
If you move away from the "STANDARD" brake fluid, it might be a good idea to note on the reservoir the type of fluid used. It will also be noted in the aircraft log book.......
Click to expand...

I run the Royco 83282 fluid ... and it earned a third of a page in my POH. I don't need it there, but the next owner will. :)
 
When to replace brake fluid?

Is there a requirement or advisory when to replace "kit standard" brake fluid? I filled and bled the lines in 2008 and added a bit of fluid last year to keep previous level. Never had problems with brakes, changed couple sets of pads that's all.
 
5 homebuilts, 68 fleet years of service and 5,100+ hours of DOT 5. No caliper corrosion, no brake failures, no worries. Nitrile O-rings and fluid changed every 20 years whether they needed it or not :D
 
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Now, that there is funny:

rv7charlie said:
A quick review of earlier threads seemed to indicate that Mobil 1 synthetic ATF is fine with stock o-rings, etc in the brake system. However, I couldn't determine whether it's ok to use it in an existing system that's had the old (5606?) fluid in it. Is it ok to use it, if I use the ATF to push the old fluid out of the system?

Also, when I bought the ATF ('multi car'), the bottle indicated that some post 2005 models need a different Mobil 1 synthetic ATF. Is either version ok for a/c brakes?

Thanks,

Charlie
Click to expand...

Hey Charlie:

I had such good luck with the Synth ATF as brake fluid that I decided to change over to it when we rebuilt the calipers on my Beech 18. It worked GREAT - for about 10 minutes. Then, we get to rebuild the master cyls and the parking brake unit, as those were probably last serviced in the early 60s by the US Navy. Yep - the 5606 kept 'em from leaking, but the synth went right past the seals. Dunno if you have ever tried to get Beech 18 master cyl seals, but they are not O rings - they are some sort of very rare umbrella seal.

Oh well - once the seals were swapped, all went according to plan. My favorite part of this change is the ability to get fluid dang near anywhere, and without hazmat shipping charges, couple days wait, etc. The Sunday morning availability aspect is not to be laughed at - I saw a gent purchase caliper O rings at Home Depot and go on his way after installation.

BUT! due to liability concerns, we use Royco 782, and aviation O rings etc, in the B25. No problems when making that change, aside from using 8 gals of fluid...:eek:

As for Dot 5, I hear it holds air in suspension, so altitude might be a factor. Maybe not till you get to 25000MSL, tho... the Dot 5 works fine on my motorcycle clutch system, but it cannot be used in the anti-lock brake system.

Carry on!
Mark
 
F1Boss said:
As for Dot 5, I hear it holds air in suspension, so altitude might be a factor. Maybe not till you get to 25000MSL, tho... the Dot 5 works fine on my motorcycle clutch system, but it cannot be used in the anti-lock brake system.
Click to expand...

I've heard this too but often fly at FL190-250 for extended periods of time and haven't had any issues. I have never, ever had to bleed the brakes between the 20 year seal swaps - and then it was just for Grandma as everything was tight and solid. [I used Cleveland brakes and master cylinders on all 5 planes]
DOT 5 available at Walmart :D

deek
 
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I'm rebuilding my brakes with vitron seals after a seal blowout on the right brake. I'm assuming that the builder and second owner used 5606, but I want to change to Mobil 1 ATF, just because. My question is do I need to flush the brake lines with the ATF, or some other solvent prior to the final "load" of Mobil 1?

Another question: My brakes and wheels are really dirty - is automotive brake cleaner OK to use on aircraft brakes and wheels?

Thanks!
 
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