Brake Fluid - Castrol LMA Dot 3 or Dot 4?

[Jim_Gruber]

Bugsy is running low on Brake Fluid and clutch needs a little added as well. Tried two local shops and no Castrol LMA to be found. Castrol Site says it is compatible with Dot 3 or Dot 4. So which is it a DOT 3 or Dot 4 Brake Fluid? I bought some Prestone Synthetic Dot 4. Will this work ok with the Castrol LMA that is in there now?

I believe so but before I add just wanted a sanity check from the list. Thanks.

 

[dklawson]

There is no easy answer.

I think you'll find the recommendation in the old manuals was Castrol LMA which as I understand it was high-end DOT-4. I suspect you'll find that standard DOT-4 is compatible with the rubber in the old brake components also. However, DOT-3 was (in the day) a no-no for use with Girling/Lockheed brake rubber. That said, sometime during the 1970s the brake rubber formulation was changed to something that is compatible with DOT-3 and DOT-4. So, if you've rebuilt your brakes (including flex hoses) since say 1980 using new (not NOS) parts, you may be OK with DOT-3 or DOT-4 and certainly with Castrol LMA. If you are at all in doubt, search for the Castrol LMA OR contact Prestone and see what they can tell you. Hopefully they've got an 800 number you can call for tech support.

 

[Jim_Gruber]

Thanks folks, I went ahead and topped things off with Prestone DOT-4 Synthetic..