Brake Fluid Recommendations?

[df2x4]

So I'm going to be replacing a generous chunk of the brake system on my red truck ('97 C1500, JB5 brake package) and I was just curious to see what everyone's thoughts on brake fluid are. I see in my owner's manual that GM specifies DOT 3 fluid. They list a part number, 12377967, which comes back as "Delco Supreme II DOT 3 Brake Fluid" and is discontinued unfortunately. I like to use GM fluids whenever possible so I dug around on Google a little and found this, ACDelco 10-4110 DOT 3 GMW brake and clutch fluid.

https://www.summitracing.com/parts/ado-10-4110

It looks to me like this should be fine to use, but the "GMW" part has me a little confused as I can't seem to find what it means.

Any thoughts or recommendations? Also out of curiosity does anyone know how much fluid the brake system holds? Trying to get a rough idea of how much I'll need to buy.

Also I've read in a few places that there really isn't much difference between fluids other than boiling point and that DOT 4 and 5.1 (NOT DOT 5) are fully compatible with DOT 3. If this is the case I could just have my mechanic use whatever he has on hand.

 

[0xDEADBEEF]

DOT 4. GM uses 4 in everything now I think.

I had no problems with 5.1 in my brake lines after a complete flush, but it destroyed the clutch line in my C5.

 

[454cid]

I buy the quart of whatever the cheap stuff is at Menard's.... (FVP Dot3, I just looked online) If I'm flushing, I'm very liberal with the amount I use. I'll go through a couple quarts since I'll do each wheel independently and will let it all drain with gravity while I'm working at each wheel.

 

[Pinger]

Also I've read in a few places that there really isn't much difference between fluids other than boiling point and that DOT 4 and 5.1 (NOT DOT 5) are fully compatible with DOT 3. If this is the case I could just have my mechanic use whatever he has on hand.

I did a bit of research on this recently (while researching seal materials) and found the same ie, stay away from DOT 5, and that DOT5.1 is fine, and compatible with the other DOTs.
DOT5.1 is what I get handed when I ask for brake fluid at my local auto store and although I'm experiencing brake problems (getting close to a solution on that) I'm pretty confident DOT5.1 isn't the cause.

Have a couple of litres (qrts) on hand to get started - you can always go back for more.

 

[df2x4]

Thanks for the responses guys.

DOT5.1 is what I get handed when I ask for brake fluid at my local auto store and although I'm experiencing brake problems (getting close to a solution on that) I'm pretty confident DOT5.1 isn't the cause.

Glad to hear you're getting close to a solution but are you positive about that last bit? I've been doing some more Googling this morning and I ended up on this Wikipedia article.

https://en.wikipedia.org/wiki/Brake_fluid

These two lines specifically make me question the use of DOT 5.1 in these trucks:

"Lack of acceptance of silicone-based fluids led to the development of DOT 5.1, a fluid giving the performance advantages of silicone, whilst retaining some familiarity and compatibility with the glycol ether fluids. DOT 5.1 is the non-silicone version of DOT 5, defined by FMVSS 116 as being less than 70% silicone. Above that threshold makes it DOT 5."

"Silicone based fluid is more compressible than glycol based fluid, leading to brakes with a spongy feeling. It can potentially suffer phase separation/water pooling and freezing/boiling in the system over time - the main reason single phase hygroscopic fluids are used."

Granted this is Wikipedia we're talking about and I'm dumb as a brick when it comes to brake fluid (hence this thread) but <70% silicone can still be "silicone based" right?

 

[Pinger]

"Silicone based fluid is more compressible than glycol based fluid, leading to brakes with a spongy feeling.

I don't think that is my problem. I think it's trapped air in the ABS, specifically the drivers side front circuit. I've devised a method of bleeding it but got rained off yesterday but with the little I got done I'm pretty sure I can detect improvement. If the rain stays off I'll get more done this afternoon and feed it back to my thread on the topic.

Also, I think I can get a (used) Snap-On scan tool in the UK at a reasonable price if needed. Off to ask Shurkey if it's the same as he mentioned using.

 

[SUBURBAN5]

So I'm going to be replacing a generous chunk of the brake system on my red truck ('97 C1500, JB5 brake package) and I was just curious to see what everyone's thoughts on brake fluid are. I see in my owner's manual that GM specifies DOT 3 fluid. They list a part number, 12377967, which comes back as "Delco Supreme II DOT 3 Brake Fluid" and is discontinued unfortunately. I like to use GM fluids whenever possible so I dug around on Google a little and found this, ACDelco 10-4110 DOT 3 GMW brake and clutch fluid.

https://www.summitracing.com/parts/ado-10-4110

It looks to me like this should be fine to use, but the "GMW" part has me a little confused as I can't seem to find what it means.

Any thoughts or recommendations? Also out of curiosity does anyone know how much fluid the brake system holds? Trying to get a rough idea of how much I'll need to buy.

Also I've read in a few places that there really isn't much difference between fluids other than boiling point and that DOT 4 and 5.1 (NOT DOT 5) are fully compatible with DOT 3. If this is the case I could just have my mechanic use whatever he has on hand.

I bought 3 qts of brake fluid for the burb and it was wayyyyyyy to much. So much that I on purposely bleed and flushed my brake til it got clear and still got brake fluid...... I think 1 qt plenty for a c1500 pick up. If you were local I would give you my other qt lol. I also used dot3 but just did that because of the manuel. Didnt know out the other dots

 

[df2x4]

So after a few hours of research here's what I've come up with...

It looks like DOT 3 and 4 are relatively similar in composition except DOT 4 has added Borate Ester to help raise the boiling points. I've seen it alleged in multiple places that DOT 3 doesn't absorb moisture as rapidly as DOT 4 (and therefore doesn't need to be changed as often), but no evidence to back that up other than the fact that European cars typically use DOT 4 more often than DOT 3 and have more frequent recommended brake fluid maintenance than American cars. I've also seen it alleged that the Borate Ester in DOT 4 can cause buildup in the lines and calipers if neglected but also no concrete evidence to back that up.

I'm still hesitant about DOT 5.1 due to the silicone content, as I've read that silicone can cause certain rubber compounds to swell in addition to what I posted earlier.

Since I've never had any issues that would lead me to believe I need a fluid with a higher boiling point, I'm leaning towards sticking with DOT 3.

 

[df2x4]

I bought 3 qts of brake fluid for the burb and it was wayyyyyyy to much. So much that I on purposely bleed and flushed my brake til it got clear and still got brake fluid...... I think 1 qt plenty for a c1500 pick up. If you were local I would give you my other qt lol. I also used dot3 but just did that because of the manuel. Didnt know out the other dots

So you're saying buy three quarts...

Thanks!

 

[Pinger]

Him: ''How much brake fluid did you buy when you did that brake work on your truck?''
Me: ''Three quarts.''

Him - much later: ''Hey, I bought three quarts of brake fluid like you said and had one quart left over unused.''
Me: ''So did I.''