V8v clutch fluid

[klee168168]

Are we supposed to change the clutch fluid? I have a 13 manual 6 speed, but never changed the clutch fluid yet. I’m not sure if when you change the brake fluid, it’s the same reservoir as the clutch fluid so do it all at once?

If so, what fluid do you all recommend and how much do I need to buy?

Edited by klee168168 on Sunday 26th January 07:02

Edited by klee168168 on Sunday 26th January 07:30

[Handyman2009]

I have a 2009 Vantage 6sp manual and yes it should be flush every 2yrs (brakes/clutch) same system. I use Motul 5.1 and you will need about 1.5L to complete the full flush of the system. There are 2 nipples at each caliper and 1 for the clutch slave cylinder under the car, hope this help

[vernierMike]

I was in an Aston dealer's workshop and was given a bottle of Castrol React Performance Dot 4 brake fluid. Says it all really.

The reason you need to change hydraulic fluid (relatively) so often is that it absorbs water from the atmosphere. This reduced its boiling point and when it does boil you get gas bubble in the fluid and the fluid becomes more compressible. This means your brake pedal gets softer and in extremis hits the floor with no braking effect. Really rather alarming.

TBH every 2 years is very frequent. But it's a safety item etc so one cannot recommend anything but that... I confess my cars go 3-4 years sometimes without a brake fluid renewal although I always do it if less than 2 years before selling a car. A few pennies in the scheme of things.

Dot 4 is great for most road use. If you buy 5.1 make sure it can be mixed with Dot 4, it also needs changing more frequently as whilst it has a higher boiling point when fresh it degrades more quickly due to a greater affinity for water. There is a silicon version that cannot be mixed with mineral-based hydraulic fluid and you need a completely clean system. Avoid unless you want a total brake rebuild.

If you track the car and get the brakes really hot then you might choose 5.1. Many say it's better but it needs changing every 6 months or so. I use Pagid Dot 5.1 in my track bikes. Some Dot 4's have very high boiling points such as Motul RBF 600.

[klee168168]

I was looking at the Motul dot 5.1 which is about $12 per bottle and the Motul dot 4 rbf600 which is a little more at $16 per bottle. The rbf600 has higher boiling points. Dot 4 rbf600 > Dot 5.1 Some owners told me if I do not track my car and use it for everyday spirited driving, then I won’t be able to tell the difference. True? I plan to change every 2-3 years.

Edited by klee168168 on Sunday 26th January 19:20

[telum01]

klee168168 said:

Are we supposed to change the clutch fluid? I have a 13 manual 6 speed, but never changed the clutch fluid yet. I’m not sure if when you change the brake fluid, it’s the same reservoir as the clutch fluid so do it all at once?

If so, what fluid do you all recommend and how much do I need to buy?

Edited by klee168168 on Sunday 26th January 07:02

Edited by klee168168 on Sunday 26th January 07:30

The service interval for the brake fluid is every two years. The clutch line uses the same fluid from the same reservoir, but it's very commonly overlooked. I've flushed the clutch line on a few cars while doing the brake service that was so bad that the owners called me up afterwards asking what I did to the clutch as it felt brand new.

How much you need depends on how much you want to flush the lines. I include 3x 500ml bottles with my maintenance kits to ensure there's enough for a comprehensive flush, but you can get away with 2 bottles if you're watching how much you go through (I don't think it's worth the risk of running out to save ~$12).

If you're doing it yourself, I have a write-up on Redpants that shows the brake and clutch lines.

klee168168 said:

I was looking at the Motul dot 5.1 which is about $12 per bottle and the Motul dot 4 rbf600 which is a little more at $16 per bottle. The rbf600 has higher boiling points. Some owners told me if I do not track my car and use it for everyday spirited driving, then I won’t be able to tell the difference. True? I plan to change every 2-3 years.

Motul DOT 5.1 is a fantastic fluid for the street. If you track your car, I'd definitely recommend getting RBF600. If you don't, the DOT 5.1 will be fine. You can use RBF600 without issue in street driving, too, it just costs more and you'd be spending extra for no reason if you don't track your car.

[vernierMike]

klee168168 said:

I was looking at the Motul dot 5.1 which is about $12 per bottle and the Motul dot 4 rbf600 which is a little more at $16 per bottle. The rbf600 has higher boiling points. Dot 4 rbf600 > Dot 5.1 Some owners told me if I do not track my car and use it for everyday spirited driving, then I won’t be able to tell the difference. True? I plan to change every 2-3 years.

Edited by klee168168 on Sunday 26th January 19:20

True. Good quality Dot 4 is more than fine for everyday motoring with our cars. I use if for all but tracked vehicles.

I'd say 5.1 is only really worth it for extreme repeated high speed braking.

[telum01]

vernierMike said:

True. Good quality Dot 4 is more than fine for everyday motoring with our cars. I use if for all but tracked vehicles.

I'd say 5.1 is only really worth it for extreme repeated high speed braking.

Strictly looking at DOT 4 vs DOT 5.1 isn't an accurate comparison and shouldn't be "the" metric to use to pick which fluid you're using. It's something to check, yes, but so long as you're getting DOT 4 or DOT 5.1, you're good. But for any brake fluid within those two categories, you need to check the actual specs for comparison between them. For example, Motul DOT 5.1 is a DOT 5.1 fluid (obviously).
Motul RBF600 is a DOT 4 fluid.
Even though DOT 5.1 has higher *minimum* standards than DOT 4, the RBF600 fluid has higher *actual* ratings than the DOT 5.1 fluid.

Edited by telum01 on Monday 27th January 01:01

[klee168168]

So both types of fluids should last equally as long? Is there one that is less prone to absorbing water?

When you “flush the clutch line”, is that to change the fluid for both the clutch fluid and the clutch pedal?

[vernierMike]

telum01 said:

Strictly looking at DOT 4 vs DOT 5.1 isn't an accurate comparison and shouldn't be "the" metric to use to pick which fluid you're using. It's something to check, yes, but so long as you're getting DOT 4 or DOT 5.1, you're good. But for any brake fluid within those two categories, you need to check the actual specs for comparison between them. For example, Motul DOT 5.1 is a DOT 5.1 fluid (obviously).
Motul RBF600 is a DOT 4 fluid.
Even though DOT 5.1 has higher *minimum* standards than DOT 4, the RBF600 fluid has higher *actual* ratings than the DOT 5.1 fluid.

Edited by telum01 on Monday 27th January 01:01

The proposition was that in everyday spirited driving the driver can't tell the difference and I was saying 'true'. There are differences in 4 and 5.1, noticeably viscosity with 5.1 thinner. Makes chasing the bubbles when bleeding air mildly more fun but this won't be an issue if you get the garage to do it or you are just flushing a sealed, air-free system.

Boiling point differences noted further up the thread!