Since Castrol GTLMA seems to be no longer available...

[DaveW]

What would you use to replace it? I liked its lubricity (long seal life) and low moisture absorption. Any reputable supplier I would trust doesn't have it.

I wouldn't mid a reasonable upgrade in function (wet & dry boiling points) and price, but would like to retain its low friction characteristics.

I've been driving myself nutty looking at brake fluid specs and suppliers.

https://www.lelandwest.com/brake-flu...ison-chart.cfm

[Steve Demeter]

https://www.unitedspeedracing.com/pr...021No8zvnrduzE


I found DOT 4 Castrol here above

[DaveW]

https://www.unitedspeedracing.com/pr...021No8zvnrduzE


I found DOT 4 Castrol here above

This is what I found on the web:
From Castrol:
There is no shelf life for Castrol GT LMA, however we would suggest that for maximum protection and performance, the product be used within 2 years of the date of manufacture. Regardless of the storage conditions, moisture can get into the product via osmosis through the plastic.

United Speed responded that they had just one 1-qt bottle, and said they think it's been discontinued, as I thought. So I declined to order it since I may as well find something else that is still being made and is not already several years old. I have 8 12-oz bottles left, but since they're >5 years old, I'll use them for my street vehicles or in the clutch system.

I have found a couple of currently made brake fluids that look good, but wanted opinions on what and why people liked a particular fluid before I decide.

[stonebridge20]

This is what I found on the web:
From Castrol:
There is no shelf life for Castrol GT LMA, however we would suggest that for maximum protection and performance, the product be used within 2 years of the date of manufacture. Regardless of the storage conditions, moisture can get into the product via osmosis through the plastic.

United Speed responded that they had just one 1-qt bottle, and said they think it's been discontinued, as I thought. So I declined to order it since I may as well find something else that is still being made and is not already several years old. I have 6 or 8 12-oz bottles left, but since they're >5 years old, I'll use them for my street vehicles.

I have found a couple of currently made brake fluids that look good, but wanted opinions on what and why people liked a particular fluid before I decide.

Dave, I'm switching all my customer street cars (mostly British sports cars) over to Valvoline DOT4 as they cycle through for their 2 year fluid services or any brake work that requires a flush of the system.
Luckily I'm sitting on 5 cases of Castorol for the race cars.
As an FYI....Scotty Young recommends cheapo DOT 4 for annular slaves. He said that the seals seem to puke prematurely when using anything fancy.

[tlracer]

Comparing the product data sheet for GT LMA to Castrol Brake Fluid DOT4, they are virtually identical:

GT LMA: https://mossmotors.com/media/instruc...20-455-505.pdf
DOT4: https://www.castrol.com/content/dam/...ot-fluid-4.pdf

Alternatively Castrol React Performance DOT4:

https://www.castrol.com/content/dam/...mance-dot4.pdf

[DaveW]

Comparing the product data sheet for GT LMA to Castrol Brake Fluid DOT4, they are virtually identical:

GT LMA: https://mossmotors.com/media/instruc...20-455-505.pdf
DOT4: https://www.castrol.com/content/dam/...ot-fluid-4.pdf

Alternatively Castrol React Performance DOT4:

https://www.castrol.com/content/dam/...mance-dot4.pdf

Thanks, but I've spent 1.5 days surfing the web, and at multiple vendors and on the Castrol website, the only Castrol brake fluid I can find except for scattered small quantities of leftover old stock is Castrol React SRF, the ~$70/L stuff. So that's why I posted this thread. None of the varieties you posted seem to be available.

So I'm resigned to using something else for my brake system this coming season and I want to know what others use.

[DaveW]

Dave, I'm switching all my customer street cars (mostly British sports cars) over to Valvoline DOT4 as they cycle through for their 2 year fluid services or any brake work that requires a flush of the system.
Luckily I'm sitting on 5 cases of Castrol for the race cars.
As an FYI....Scotty Young recommends cheapo DOT 4 for annular slaves. He said that the seals seem to puke prematurely when using anything fancy.

Thanks for the info...
When I replaced the SAAB slave seals this fall, I flushed the clutch hydraulics with Valvoline DOT 4 because I'm very low on the Castrol DOT 4 fluid. So I'll just keep using that there.

[tlracer]

Thanks, but I've spent 1.5 days surfing the web, and at multiple vendors and on the Castrol website, the only Castrol brake fluid I can find except for scattered small quantities of leftover old stock is Castrol React SRF, the ~$70/L stuff. So that's why I posted this thread. None of the varieties you posted seem to be available.

So I'm resigned to using something else for my brake system this coming season and I want to know what others use.

Apologies for any confusion, I was just trying to illustrate that GT LMA isn't fundamentally different in spec from a good-quality DOT4 product and that the horribly expensive stuff doesn't - in my mind - justify the price, as they're all basically the same for boiling points (dry & wet), viscosity, etc.

This is a cheap DOT4 available here in the UK at around £7 per litre (about $9) and has the same tech spec as the others:

https://www.commaoil.com/passenger-v...iew/197/BF41L/

Typical Inspection Data:
Density @ 20°C 1.048 g/cm3
Viscosity @ -40°C 1300 cSt
Viscosity @ 100°C 2.3 cSt
Colour Colourless to amber
Equilibrium Reflux Boiling Point 265°C
Wet Equilibrium Reflux Boiling Point 160°C
pH (50% EtOH) 9.1

[DaveW]

Those have excellent boiling temperature specs and are relatively inexpensive at ~$7 and $14 for 12-oz bottles. If nothing obvious shows up that racers like more or has been demonstrated to perform better I may wind up getting one of those.

Amsoil Synthetic DOT 4 BFLV: 368F W, 520F D
Amsoil Dominator DOT 4: 410F W, 580F D

[DaveW]

Apologies for any confusion, I was just trying to illustrate that GT LMA isn't fundamentally different in spec from a good-quality DOT4 product and that the horribly expensive stuff doesn't - in my mind - justify the price, as they're all basically the same for boiling points (dry & wet), viscosity, etc...

Thanks, I understand.

There are a LOT of DOT 4's here in that range. I am looking for something a little better in boiling temp specs that doesn't have any obvious downsides like poor lubricity.

[bassracer]

Without much time to research the fine details, I decided to go for valvoline dot 4 last year.

[Phil Creighton]

Dave
We use SRF on pretty much everything unless the manufacturer specs a particular brand and you need to be nice to them.
While expensive its just bulletproof and takes out all the issues of overheating - better pedal because of less compressability and its not hygroscopic (does not absorb moisture) so its a fill and forget fluid.
1/2 a can for an FC car fill up .......................
I agree on the cheap stuff for annular bearing seals - more inherent lubricity I was told many years ago.
Phil

[teamwisconsin]

Amsoil Synthetic DOT 4: 368F W, 520F D
Amsoil Dominator DOT 4: 410F W, 580F D

We switched to the Amsoil Dominator Dot 4 for all applications that used GTLMA. Been using it for a few years now happily with dozens of FF's for brake and clutch, we also use it in FA and F1 applications for clutch fluid for it's lubricity and keeping the seals happy.

[bassracer]

Curious what is being used to understand difference in lubricity?

[Steve Demeter]

Well it looks like I just squeaked in with my order for 2 quarts from United Speed yesterday

[DaveW]

Curious what is being used to understand difference in lubricity?

My only measure is how quick the fluid gets dirty from wear particles or how long seals last w/o issues.

Also, in most sliding seal applications, lower viscosity (everything else remaining equal) means more rapid seal wear.

[DanW]

My only measure is how quick the fluid gets dirty from wear particles or how long seals last w/o issues.

Castrol DOT4 in my FF and Lotus 23. Brakes in the 23 run much hotter due to limited air cooling, but still work fine.

With 4 seasons and 60 hours I found the annular clutch slave o-rings with light wear, but the sleeve had a lot of fretting corrosion that had worn through the anodizing on the sleeve. The fretting corrosion would seem to happen regardless of fluid since most occurs on the atmospheric side of the o-ring.

[stonebridge20]

Castrol DOT4 in my FF and Lotus 23. Brakes in the 23 run much hotter due to limited air cooling, but still work fine.
.

When I was prepping 355 and 360 Ferrari challenge cars, they both got GTLMA as well as the 53 MGTD racecar I still prep and everything in-between with zero problems. I used it in all my Atlantic cars including my DB4 with no cooling ducts at Montreal which is brutal on brakes.

It ticks me off that you can't get the stuff anymore.

[DanW]

When I was prepping 355 and 360 Ferrari challenge cars, they both got GTLMA as well as the 53 MGTD racecar I still prep and everything in-between with zero problems. I used it in all my Atlantic cars including my DB4 with no cooling ducts at Montreal which is brutal on brakes.

It ticks me off that you can't get the stuff anymore.

Just speculation, perhaps Castrol repackaged GTLMA to DOT 4 for marketing purposes. Maybe contact Castrol tech support directly?

[DaveW]

When I was prepping 355 and 360 Ferrari challenge cars, they both got GTLMA as well as the 53 MGTD racecar I still prep and everything in-between with zero problems. I used it in all my Atlantic cars including my DB4 with no cooling ducts at Montreal which is brutal on brakes.

It ticks me off that you can't get the stuff anymore.

Just speculation, perhaps Castrol repackaged GTLMA to DOT 4 for marketing purposes. Maybe contact Castrol tech support directly?

On the Castrol website, neither LMA or equivalent DOT4 brake fluid is shown - only the expensive React SRF fluid.

[tlracer]

Just speculation, perhaps Castrol repackaged GTLMA to DOT 4 for marketing purposes. Maybe contact Castrol tech support directly?

Yes, that's exactly what they did. This is copied from a Jaguar E-Type forum when someone asked Castrol:

"I asked Castrol. Here is their reply:

''This ticket has been updated by LT - Castrol Representative


Thank you for contacting Castrol North America.


Castrol GTLMA was rebranded as Castrol Brake Fluid DOT 4 – the fluid is the exact same.


Castrol Brake Fluid DOT 4 is sold at retailers such as Wal-Mart and is also available at all major Auto Parts retailers such as AutoZone, Advance Auto Parts, O’Reilly, Pep Boys, Strauss, NAPA and by select quick lubes, dealerships and auto service centers around the country.


The above mentioned national retailers who carry Castrol products order their products from a warehouse, who in turn, order the product from us. Generally it is based on consumer demand therefore we are unable to advise you of a specific retail location that carries that particular product – please call the surrounding stores directly to inquire about product availability.


Authorized state distributors are also an option however the state that you are located in is required for us to provide you with the appropriate company and contact number – if you are interested in this offer, please advise.


Castrol Consumer Relations’’

[DaveW]

On the Castrol website, neither LMA or equivalent DOT4 brake fluid is shown - only the expensive React SRF fluid.

Yes, that's exactly what they did. This is copied from a Jaguar E-Type forum when someone asked Castrol:

"I asked Castrol. Here is their reply:...Castrol Brake Fluid DOT 4 is sold at retailers such as Wal-Mart and is also available at all major Auto Parts retailers such as AutoZone, Advance Auto Parts, O’Reilly, Pep Boys, Strauss, NAPA and by select quick lubes, dealerships and auto service centers around the country...

Castrol Consumer Relations’’

I searched online over the last few days for Castrol DOT 4 brake fluid and most hits were across the pond. Almost nothing here in the US. And nothing from any supplier in the US that I would trust had fresh stock.

[tlracer]

Based on all DOT4 fluids needing to meet minimum specifications, I can't see there is, a massive amount to choose between them. Certainly the BP values aren't different enough, you would need to go up to a DOT5.1 fluid for that. Confusingly, these are glycol based, unlike DOT5...

There are some variations in viscosity, which affects flow. As lower viscosity gives better flow rate, you'd think that would be the ideal; however, I suspect significantly lower viscosity might begin to facilitate leakage past seals?

All considered, I'd select a few known and available names, compare datasheets for similarly with your previous fluid-of-choice and buy the closest fit (assuming a fair price!)

[DaveW]

Based on all DOT4 fluids needing to meet minimum specifications, I can't see there is, a massive amount to choose between them. Certainly the BP values aren't different enough, you would need to go up to a DOT5.1 fluid for that. Confusingly, these are glycol based, unlike DOT5...

There are some variations in viscosity, which affects flow. As lower viscosity gives better flow rate, you'd think that would be the ideal; however, I suspect significantly lower viscosity might begin to facilitate leakage past seals?

All considered, I'd select a few known and available names, compare datasheets for similarly with your previous fluid-of-choice and buy the closest fit (assuming a fair price!)

That's exactly what I've been doing and Amsoil Dominator seems to have close to the best characteristics, if one doesn't include SRF in the comparison. And its price is quite reasonable if you include Amsoil's preferred customer discount.

I just ordered a case (12) of 12-oz-bottles of Amsoil Dominator DOT 4 brake fluid. $162 including $10 preferred 6-mo membership, sales tax, and free shipping. So it was $11.77/bottle w/o tax or the membership.

Thanks to everyone who offered their opinion. These responses are much appreciated.

[DaveW]

...There are some variations in viscosity, which affects flow. As lower viscosity gives better flow rate, you'd think that would be the ideal; however, I suspect significantly lower viscosity might begin to facilitate leakage past seals?...

I don't think lower viscosity would have a significant effect on leakage past the seals if they're in good shape. However, lower viscosity means a thinner "boundary" layer of fluid cushioning the seals from abrasion and wear. So the effective better lubricity of a higher-viscosity fluid "should" prolong seal life.

That's one of the reasons I ordered Amsoil Dominator instead of the lower priced and lower-viscosity ABS-friendly Amsoil DOT 4 BFLV.

[stonebridge20]

I searched online over the last few days for Castrol DOT 4 brake fluid and most hits were across the pond. Almost nothing here in the US. And nothing from any supplier in the US that I would trust had fresh stock.

So here's the deal with Castrol DOT4/GTLMA

Castrol is no longer making GTLMA which was rebranded as Castrol DOT4 because they can no longer get Glycol Esther's.

You will not find anyone selling anything other than old stock GTLMA or Castrol DOT4 in the USA.

Yes, I called Castrol.

[DaveW]

So here's the deal with Castrol DOT4/GTLMA

Castrol is no longer making GTLMA which was rebranded as Castrol DOT4 because they can no longer get Glycol Esther's.

You will not find anyone selling anything other than old stock GTLMA or Castrol DOT4 in the USA.

Yes, I called Castrol.

I would have "liked" this but it's not great news and confirms what I thought. That's why I just bought the Amsoil BF.

[tlracer]

I don't think lower viscosity would have a significant effect on leakage past the seals if they're in good shape. However, lower viscosity means a thinner "boundary" layer of fluid cushioning the seals from abrasion and wear. So the effective better lubricity of a higher-viscosity fluid "should" prolong seal life.

That's one of the reasons I ordered Amsoil Dominator instead of the lower priced and lower-viscosity ABS-friendly Amsoil DOT 4 BFLV.

Agreed. I was thinking mainly about seals that had been in use when I mentioned leaking. Though your point about a thinner boundary layer does make me wonder about the supposed flow benefits of lower viscosity fluid.

On balance my view would be the same as yours, a higher viscosity and comparable BP's.

[DaveW]

Agreed. I was thinking mainly about seals that had been in use when I mentioned leaking. Though your point about a thinner boundary layer does make me wonder about the supposed flow benefits of lower viscosity fluid.

On balance my view would be the same as yours, a higher viscosity and comparable BP's.

The lower viscosity fluid was developed to allow ABS and other (traction control using the brakes, etc.) fast response systems using brake fluid to function properly at temperatures as low as -40F (C). AFAIK, there was no other reason for its creation.

In most racecars where the braking system is never that cold and doesn't need super-fast response it has little to no advantage.

[DaveW]

Castrol DOT4 in my FF and Lotus 23. Brakes in the 23 run much hotter due to limited air cooling, but still work fine.

With 4 seasons and 60 hours I found the annular clutch slave o-rings with light wear, but the sleeve had a lot of fretting corrosion that had worn through the anodizing on the sleeve. The fretting corrosion would seem to happen regardless of fluid since most occurs on the atmospheric side of the o-ring.

Fretting on the atmospheric side is one of the reasons I use a liberal amount of brake grease to assemble the clutch slave and any other brake component like cylinders or calipers. The only downside is that grease attracts dirt. So a shield/bellows on the air side is important.

[kdl]

I went through this exercise earlier this year and settled on Ford's motorcraft high performance DOT4 LV (PM-20) the wet/dry boiling points were slightly higher than Castrol (lubricity have no idea how that compares) and price/availability was acceptable. I have no on track comparison as I had sufficient Castrol to finish the season.
Keith

[FVRacer21]

Has anyone tested the new DOT 5.1 brake fluids?

"BRAKE FLUID DOT 5.1 is a brake fluid for hydraulic brake and clutch systems with a boiling point of at least 260 °C (356F) and an extremely high wet boiling point of at least 180 °C (500F). Because of the low viscosity at low temperatures, particularly suitable for additional systems, such as ABS and ASR." From Motex

Now 5.1 is NOT the same as 5 (Silicone) (Thanks whoever came up with a confusing rating system)

Prestone's version is available at Advance Auto for $16 for 12 oz
Summitt Motul DOT 5.1 Brake Fluid 100951 for $10.00

With a FV DOT 4 works fine, but what is the class where you need those figures?

ChrisZ

[DaveW]

As I said in a previous post, the LV brake fluids are not likely to have the same level of lubricity as the regular DOT 3 & 4 fluids and thus usually cause faster seal wear. For instance, my rear dampers use a lower viscosity oil than the fronts to minimize temperature effects, and I was told by Steve Horn at Penske that the rears would need rebuilding more often than the fronts because of it.

This faster wear is due to the thinner protective fluid layer between the seal and what it's sliding on when using a lower viscosity fluid.

While the higher temperature ratings of a 5.1 are enticing, I won't be using a LV brake fluid because of the lower lubricity.

There are fluids that maintain their lubricity AND have higher boiling points.

https://www.lelandwest.com/brake-flu...ison-chart.cfm

If you read this entire thread, you'll see a lot more info.

[FVRacer21]

As I said in a previous post, the LV brake fluids are not likely to have the same level of lubricity as the regular DOT 3 & 4 fluids and thus usually cause faster seal wear. For instance, my rear dampers use a lower viscosity oil than the fronts to minimize temperature effects, and I was told by Steve Horn at Penske that the rears would need rebuilding more often than the fronts because of it.

..............

I would agree, but think we need to get someone to quantify this.

Here is a quote from another supplier of 5.1 fluid:

"Optimal Lubricity which avoids the abrasion of the brake system by friction."

https://www.peakoil.com.au/brake-flu...fluid-dot-5-1/

I would think "Optimal" means they put additives in just for that reason.

Note: others have used "outstanding", "excellent", etc. - Give me a number!

Sounds like we need some sort of objective rating, like zddp in oil.....

Unfortunately, from down under, but maybe some of our Australian correspondents can chime in.

Any brake fluid suppliers at PRI?

ChrisZ

[DaveW]

...Here is a quote from another supplier of 5.1 fluid:

"Optimal Lubricity which avoids the abrasion of the brake system by friction."

https://www.peakoil.com.au/brake-flu...fluid-dot-5-1/

I would think "Optimal" means they put additives in just for that reason.

Note: others have used "outstanding", "excellent", etc. - Give me a number!...ChrisZ

That sort of language is, IMO, "corporate-speak", an attempt to counter the generally-recognized fact that lower viscosity fluids/lubricants don't have lubricity equivalent to higher viscosity ones, everything else being equal.

However, it WOULD be nice to have some actual test data on this subject. Unfortunately, most manufacturers tend to be very secretive about this sort of testing.

The lubricity issue is one of the reasons I chose the Amsoil Dominator fluid. Amsoil has for almost 50 years been recognized for their expertise in tribology (the study of friction, wear, lubrication, and the design of bearings; the science of interacting surfaces in relative motion).

https://www.amsoil.com/about/

Disclaimer: Other than using some of their products, I have no connection with Amsoil.

[Hardingfv32]

This concern over 'lubricity' seems a little misguided. Road car brake systems, even those using low viscosity brake fluid, go ten's of thousands of miles without any wear issues. Ever seen a callout in the maintaince schedule to rebuild the master cylinder? How can it be an issue for race cars that only go a 3-4 thousand miles at most?

Brian

[DaveW]

This concern over 'lubricity' seems a little misguided. Road car brake systems, even those using low viscosity brake fluid, go ten's of thousands of miles without any wear issues. Ever seen a callout in the maintaince schedule to rebuild the master cylinder? How can it be an issue for race cars that only go a 3-4 thousand miles at most?

Brian

I guess all of us racing folks are misguided, our experience means nothing, and all the BF companies that are stressing that their LV fluids in spite of being LV have high lubricity are all dumb since lubricity is not important...

[E1pix]

I hear that, Dave.

Maybe if Harding actually wins anything, we can all be as enlightened.

[tlracer]

C'mon guys, let's not start having a pop at individuals...Apexspeed is better than that.

There are both similarities and differences between race and road applications, but ultimately the required job is the same, to make the brakes work, consistently over repeated applications.

Clearly there's no definitive 'go to' brake fluid; discounting silicone fluids as they're not compatible with anything else, either DOT4 or DOT5.1 specifications give a minimum requirement. Whilst the brake operations are different, the fluid requirements are remarkably similar, hence the analytes within the specifications.

Getting bogged-down in brands is irrelevant. Identify your needs, which drivesl the required specifications, and buy.

[E1pix]

Appreciate that 100% — but DaveW is pretty regularly being put in a defensive position by only *one person* on this forum.

Dave’s the US version of your Morris, so deserves respect for his accomplishments over 55 years — and was also an engineer. Sometimes nothing else works in such matters, and even then still doesn’t.