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[mathewst]

Need to change this.
But I've read a few articles and they mention dot 5.1 is better than dot 4 oil and intendet to go in brakes with abs systems.
Which one to use?
Also how much oil will be needed (in litres please) if someone knows?
Thanks in advance

[Richgm]

HI Mathew,
First things first to make sure there is no confusion, it's brake fluid not oil.
Dot 5.1 has a higher boiling point than Dot 4 but unless your going to use the car on the track or drive like a lunatic then it's not going to make that much difference to you.
Personally I would use what ever you already have in there as I don't like mixing different types and as for how much I would guess at less than 1 litre.

[mathewst]

Thanks Richgm and sorry for the mistake (fluid / oil) we usually call it oil here. I saw something thad said 5.1 fluid is more durable than  dot4 that's why was asking. Don't plan to drive around track definitely.

[Jimbob]

interesting question though, if going for a full flush, is going to 5.1 a worthwhile upgrade?  to GM do a 5.1?  what is the price difference?

[mathewst]

JimBob the price for dot5.1 is double for one liter as far I've seen. But read that it should last twice as longer

[bigdods]

I have been told by a man who knows these things that the below apply (hopefully I have correct repeated his words of wisdom!):

You can replace 4 with 5.1 , just drain the old fluid and replace

5.1 is better suited to track work as it is less prone to boiling (I think he said higher boiling point and some technical stuff about viscosity that went over my head)

NEVER mix 5 with 5.1 or 4 . 5 (without the .1) is someting totally different

5.1 and 4 last the same time unless the brakes get very hot, then the 5.1 will last significantly longer

Degradation in brake fluid is usually due to water contamination over time this affects both 4 and 5.1

[Kevin Wood]

Yep. Don't touch DOT 5 as it's silicone based and generally not worth the bother.

DOT 5.1 is a mineral fluid similar and compatible with DOT 4 but with better high temperature performance.

Probably won't make a noticeable difference unless you are taking the car on track, as said.

I would say buy 2 litres for a fluid change. Don't buy more than you need as it goes off in the bottle and try to avoid using fluid from a bottle that's been open for a while for anything other than topping up.

Kevin

[mathewst]

Ok thanks guys for the help. Will snoop around the stores and try to find the prices around here for the oils.
If the difference isn't big I'll buy dot5.1.
Although if anyone else knows excatly how much brake fluid I need to buy I would really appreciate the info.

[Omegatoy]

have run 5.1 in all my motors since it came out!! it is better thaN DOT 4 AND YES MINE DOES GET DRIVEN LIKE A LUNATIC  (especially when the boy drives it) and as said it doesnt absorb as much moisture as 4, however out here with the temp around 37 at mo it gives me greater peace of mind to know its not asprone to boiling going up and down the mountains or as  hydr0scopic as 4,
easiest way to describe it is similar to the difference between mineral 10/40 and semisynth 10/40, you just know its going to give better performance!!!

[Richgm]

Ok thanks guys for the help. Will snoop around the stores and try to find the prices around here for the oils.
If the difference isn't big I'll buy dot5.1.
Although if anyone else knows excatly how much brake fluid I need to buy I would really appreciate the info.

Just found this on the TIS CD but I must admit I think it sounds a little on the low side.

Brake Fluid

Quality:
 Opel/Vauxhall high performance brake fluid. This brake fluid conforms to US safety standard DOT4 and SAE-specification J 1703. This brake fluid may be mixed with all fluids conforming to these regulations.
 
Change interval:
 Opel/Vauxhall heavy duty brake fluid must be changed every 2 years – see Brochure "Inspection System" or "Inspection System/Service Plan" valid for the relevant Model Year.
 
 Approximately 0.5 litres
 

[TheBoy]

1l should be enough for a flush, even if you waste a lot