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Changing the fluid in the brake lines at the weekend , sure the last time I used 5.1 synthetic am I right in saying that this grade is more suited to heavy use .

Hi John1000, I believe there were issues with what was considered a race item Dot 5.1 fluid, some formulas eroded rubber seals. I believe most formulations are now OK but read this http://www.xs11.com/tips/maintenance/maint1.shtml

I used 5.1, but I have no clue why

You should use what it says on the resevoir cap, dot 4 in this case!

loafersmate wrote:You should use what it says on the resevoir cap, dot 4 in this case!

He's right

Aprilia manual lubricant chart for recommended brake and clutch fluid:
IP F.F., DOT 5 (DOT 4 compatible) or Agip BRAKE 5.1, DOT 5 (DOT 4 compatible).

Ok so I guess its ok to use because it says will mix with dot 4 .
Thanks for the replies always good to get a second opinion thanks for the link Thumper but to much info for my small brain.

There was a big discussion on AF1 on this.

From memory (ie This Needs Checking Before You Act On It) it's OK to use DOT 4 or 5.1 but not DOT 5 as it's quite different. I'm pretty sure they concluded that the DOT 5 was a misprint because it isn't the same as DOT 4.

I'll go and search for this and edit this if I find anything.

EDIT:
Yep read these links to discover more:
http://www.apriliaforum.com/forums/show ... hlight=DOT
http://www.apriliaforum.com/forums/show ... hlight=DOT

I'd read these in conjunction with the link posted by Thumper for the best understanding.

Anyway - the advice is Avoid DOT 5

Basically you don't need dot 5, dot 4 is more than adequate for a road bikes so that's what I use.
However fluid speck moves on and more manufactures are producing higher spec fluids now.
Many falco owners were having problems with clutch cylinders leaking in the last few years and I was reading about troublesome brake master cylinders also, these things are usually very reliable.
I suspect the systems were being filled with Dot 5 fluids and it was causing premature failure of seals but It's only a hunch, I have no evidence for that.

Just to add some confusion:
http://www.apriliaforum.com/forums/show ... stcount=12

sabestian wrote:Just to add some confusion:
http://www.apriliaforum.com/forums/show ... stcount=12

Just as on our forum, over on AF1 some posts within a thread are more helpful than others.
Read the whole thread, understand what is consistent and check against other authoritative sources -like the link that Thumper posted.

You use the brakes?

Falcoholic wrote:You use the brakes?

That was my first thought.
I concluded it must be a Falco rider thing.

Falcoholic wrote:You use the brakes?

It's for MOT!