Quote:
Originally Posted by tirwin
Thanks. I was just trying to figure out if there is anything real behind "DOT 4+" (having never heard of it before) or if it is just some marketing gimmick to buy brake fluid from MB.
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it's a marketing gimmick,
DoT 4 - 'In the United States, all brake fluids must meet Standard No. 116; Motor vehicle brake fluids.[1] Under this standard there are three Department of Transportation (DOT) minimum specifications for brake fluid. They are DOT 3, DOT 4, and DOT 5.1. DOT 4, like DOT 3 and DOT 5.1, is a polyethylene glycol-based fluid (contrasted with DOT 5 which is silicone-based). Fluids such as DOT 3, 4, and 5.1 are hygroscopic and will absorb water from the atmosphere. This degrades the fluid's performance, and if allowed to accumulate over a period of time, can drastically reduce its boiling point. In a passenger car this is usually not much of an issue as the brakes are generally not used aggressively, but can be of serious concerns in police vehicles, racecars or motorcycles due to the higher heat generated during their much more aggressive braking, and trucks where higher heat can be generated while braking hard and fully loaded.
While a vehicle that uses DOT 3 may also use DOT 4 or 5.1 if the elastomers in the system accept the borate compounds that raise the boiling point,[citation needed] (a temperature upgrade) a vehicle that requires DOT 4 might boil the brake fluid if a DOT 3 (a temperature downgrade) is used. Additionally, these polyglycol ether based fluids cannot be mixed with DOT 5.0, which is silicone based.
As of 2006, most cars produced in the U.S. use DOT 4 brake fluid.'
here are some commonly used dot 4 dry & wet boiling points
Castrol React SRF 4 518 608
Endless RF 650 4 424 622
Motul RBF 600 4 401 594
Pagid RBF 4 399 626
ATE Typ 200 4 388 536
ATE SL.6 4 338 509
Castrol DOT 4 4 311 509
ATE 200 is the most common Euro oe fill