I still don?t get that GTLMABCD stuff. is it because on the continent over here this DOT4 stuff is a bit different ? I don't know. I never have seen or heard of special DOT4 brake stuff. DOT4 is always DOT4 over here as far as I know. I'm not an expert but never ever did I hear of anything different, I always only read it here on the DML. If anybody knows facts about differences from here to there - please let me know. BUUUT ! there is DOT5 and DOT5.1 DOT5 is silicon based and can not be mixed. DOT5.1 is NOT silicone based and can be mixed with lower grades. DOT = Departement Of Transportation -> why do we use that over here if it is different ? this took me like 5 minutes by Google to find out. The rest about DOT5 is the same as I read on other forums. People often see a higher number and think they need to have that. The result wasn't always positive. I own 6548. cool number, had to have that :-) Elvis According to the manufacturers you can mix a higher DOT # with lower ones but you end up with the lower # fluid as far as boiling points is concerned. IMHO I would not EVER mix DOT 5 with anything. In fact if you wanted to convert to DOT 5 I recomend complete disassembly of ALL parts and a flush with alcohol and brushes before putting DOT 5 in. Same deal if you ever had DOT 5 in the system and you want to go back to DOT 4. A lot of antique cars tried DOT 5 silicone because it was not hygroscopic figuring the fluid would not rot the systems. Most discovered two big problems. One, DOT 5 contains tiny air bubbles that you cannot remove. They make it slightly compressable which increases pedal travel. On many older cars, especially with drum brakes, it means you have to pump the pedal to stop the car. The other problem is since water will not mix into the silicone, it builds up into globules and goes to the lowest points in the system. Bleeding will not get it out, the bleeders are at the high points. It lays in the low spots and rots the metal parts. Dot 4 Castrol GTLMA is fine for street driving. If you change it every 2 years you will never have a problem with corrosion or boiling. There are many things that are done to cars that go on a race track, putting silicone DOT 5 brkae fluid into them is one, mainly for the very high boiling point. Not everything in race cars can be used directly in street cars. David Teitelbaum vin 10757 ------------------------------------ To address comments privately to the moderating team, please address: moderators@xxxxxxxxxxx For more info on the list, tech articles, cars for sale see www.dmcnews.com To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnewsYahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/dmcnews/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/dmcnews/join (Yahoo! ID required) <*> To change settings via email: mailto:dmcnews-digest@xxxxxxxxxxxxxxx mailto:dmcnews-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: dmcnews-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/