Hi Joe.
The uses and abuses of silicone brake fluid verge on being a religious debate. Hopefully I can cover the basics without coming across as a heretic.
1. Silicone brake fluid does not damage paint, the way that regular fluid does. This is a really good thing if you have just painted your engine compartment.
2. Silicone fluid did have a higher boiling point than regular brake fluid at one time. New formulations of regular fluids now meet or exceed those of Silicone. There were some other performance advantages which have also now become moot.
3. Silicone fluid does not absorb water. This can be good and bad. Any water that enters the brake system will remain in suspension and will cause all kinds of problems when it gets hot, but the good news is that typically brake components such as wheel cylinders will not corrode. Regular fluid absorbs water which means that when it is contaminated brake components will become corroded. The important point to make is that all brake fluids should be changed on a regular basis.
4. All brake fluids contain some quantity of seal swelling additives designed to prevent the rubber piston seals from drying out. The effect of these additives can vary wildly from brand to brand and also over time. There have been instances of problems caused by swelling additives in some Silicone fluids causing problems with fluid return to the master cylinder.
After years of using various Silicone brake fluids and hearing horror stories, I can best sum up with the following:
Using the recomended Castrol LMA or Lockheed fluids in British brake systems always works well. It will eat paint if it spills or leaks.
In some cases, using Silicone brake fluid can cause problems, but if it spills or leaks, it won't damage paint.
For more information, check out the following link:
http://www.mossmotors.com/MemberServices/TechTips/TechTipsArticle.aspx?TechTipID=19&ModelID=32000&SubcompCode=J000
Kelvin Dodd
Global Sourcing Engineer
Moss Motors, Ltd.
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