Wondering if I can use DOT 5.1+?
 

Hey guys,

I looked everywhere but couldn't really find a clear answer. I know Mercedes says you have to use DOT 4+ but since DOT 5.1 is very similar to DOT 4+ I was just wondering if I can use that instead...5.1 is a few degrees higher when it comes to dry and wet boiling point.


Thanks

follow what is specified for your car!!

Just use the Mercedes specification as Plutoe said, and use their DOT4+ fluid. While they do not manufacture these fluids, it's best to stay with what you know will work. DOT4+ is not a standard, it is a Mercedes nomenclature. Here are two important resources to read more about this:

"And now back to the Brake Fluid: the MB recommendation is for MB Part No. A000 989 08 07 01, superseded by A000 989 08 07 10 and A000 989 08 07 13; according to the Vehicle Model Year the MB Sheet can be 330.1/331.0. In non-MB terminology the fluid has to be DOT4+ compliant.
And here the things get a bit confused: there is a DOT3, DOT4, DOT5 and DOT5.1 specification, but no such thing as DOT4+. The DOT4+ or DOT4 PLUS is an MB thing. Lately some manufacturers of brake fluids came up as well with new marketing ideas such as DOT4+ or DOT4 PLUS. The idea is that the fluid has to be better than DOT4.

In US, all brake fluids must meet Standard No. 116; Motor vehicle brake fluids. Under this standard there are three Department of Transportation (DOT) minimum specifications for brake fluid 3, 4 and 5.1. Most of the cars manufactured after 2006 use DOT4 brake fluid.

In conclusion, there is no DOT4+ spec., but there is a DOT5.1 spec."
http://www.benzworld.org/forums/w211...ml#post4515022


And the StopTech whitepaper on the subject... http://stoptech.com/technical-suppor...rs/brake-fluid

Hope that helps!

when considering a synthetic brake fluid (DOT5) be sure you've given thought to
the rubber parts within your system and checked with the manuf whether this
is a wise thing to do. synthetics can cause premature degrading of parts. I
don't recall that MB has recommended DOT5 on their fluids replacement listings

https://cimg0.ibsrv.net/gimg/www.mbw...46d451d69b.png

via stoptech.com


DOT 5 and DOT 5.1 have the same ERBP and viscosity limit but are two completely different fluids when it comes to composition

That's exactly what I'm talking about. If 5.1 is the same chemical composition as 3 and 4 can't I just use that? The wet boiling point of 5.1 is very close to the MB 4+.

1) Why do you want to change?


Do you think you have a problem with overheating your fluid.


2) DOT4+ (DOT4 LV (Low Viscosity)) is getting quite common on cars (particularly European)


3) All brake fluid is "Synthetic", just some like to use it as a marketing term.


4) While all brake fluid (Other the DOT5) is intercomparable, mixing brands can result in reduced performance since each company's formulation is slightly different.

Stick to Benz latest recommendation or you will experience elastomer compatibility problems & potential seal swell issues.

I would not switch. What is unknown is the effect of switching on o rings/seals and other parts in the system. You might find the system inop after using for a while. Why take the chance? SBC brakes are risky enough without adding more risk.

I agree with all (except the 2007 E350 did not have SBC)

Oh okay, I only wanted to switch because I have better access to 5.1 and the MB fluid gets pretty expensive. So I just thought that since 5.1 is compatible with 4 then maye I can use it in the system. I know that 5 is silicone and would destroy my system, just thought since 5.1 and 4 is made from almost the same chemical composition I can use them interchangeably.

....you have an urge to get version 5.1 because it feels like you'd be getting the software upgrade with the latest virus protection :)

I would bet 5.1 is fine, but it would be a bet.


If you look at the specs for 4, and 4 VL, seems like 5.1 is just the formalization of 4LV specs.


However, you are still going into uncharted territory. As viscosity goes down, typically so does lubricity. I would not worry too much about seal and such, but would worry about the ABS pump and valves.


Again, you don't need MB specific. ATE LS.6 (DOT 4 LV) is just fine (and probably what the MB fluid is).

^Agreed 100%, you can try it but why risk it.

anyone using 5.1 on their sbc pump? pls share ur experience

As was said previously, just don't try it. I've read horror stories and saw something on one of those TV car shows where they explained what could happen when you switch. It's just not worth the risk. Newer isn't always better. The system was designed for a spec and you should stay with it.

I fully flushed my 211 with SBC with Ravenol 5.1 fluid last year
It's a german made fluid, high quality.

Previously SBC was loud and activating all the time.
After changing the fluid I rarely feel/hear the SBC pump priming the fluid.

Braking performance was much better.

Definitely recommend it.
5.1 is a superior fluid over dot4.

Did you ever flush and try the recommended fluid?

I did not.

I choose 5.1 because it’s a superior spec plus it’s designed for Mercedes, hence being a superior fluid altogether in my opinion.

Ill continue to use it because it’s much cheaper than buying Mercedes branded fluid and because I’ve had no problems with it

What is the spec for the SBC cars? DOT4 or DOT4LV.

If it is LV I would not be as concerned, but if it calls for regular DOT4, I would wonder if they wanted the higher viscosity for some reason (like lubrication)
"Working Fine" is hard to tell till it stops working.

Both regular mercedes Dot 4 and Dot 4 LV are compatible.

5.1 and Dot 4 LV are the same; 5.1 just has a higher minimum spec.
Both are glycol based.
Dot 4 has higher viscosity but most applications don't matter either way.

$30 for 1 liter is too much

Who pays $3 a litre for any of it?

Yes if it is designed for 4LV, then 5.1 would be no trouble if however it is designed for 4( non- LV) and takes advantage of viscosity, then and might be too thin.
In the world of engineered fluids "better" is not always better.

Pentosin Super Dot 4 is also widely recommended in the old threads. ATE might have slightly better specs. But in any event, as others said I'd only use the fluid speced for the car. System was designed with fluids of a particular spec, who knows what will happen even if the specs of the fluid is "better". The old system doesn't know that. Pentosin is only $11-$15 a liter so it's not crazy priced like MB fluid. The LV fluid is about $1 more and the people always used the regular super dot 4. It's about $14 on Advance Auto and they always have 20% coupon codes you can use on retailmenot.com.

The German ABS systems after about 2000 seem to like the LV.
My guess is they build them to modulate the pressure quickly and high viscosity slows the pressure transfer.
Dot 5.1 is about the same in this regard as 4LV. I would not worry about moving a 4LV system to 5.1, but a system that was designed for old 4 (or even 3) might not get the lubrication it was designed for.
ATE, Pentosin, and a few other companies my perfectly fine fluid quality wise. No need to pay MB prices.

One more little tidbit each company has their own formulation to get to the desired specifications, and the specification requires that the fluids be compatible. (Little or no degradation of published specifications), but I never trust mixed fluids at their limits.
If you mix brands, it is always best to move to a shorter replacement cycle, just to be safe. (and a good way to get back to a single brand fill.)

Maybe other german makers did, but I don't think MB ever speced an LV fluid. Haven't even seen them on the shelves til the last couple years. There's a slight difference in the fluid so I'm just going to stick with regular Super Dot 4, it's also $1 a quart cheaper.