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How Much Oil - Ultegra Brake Bleed

My bike is 3 years old from new a despite new pads the brakes feel spongy - so I'm thinking of bleeding them with and refilling with replacement oil. I'm confident of the process and going to buy a kit but not sure how much oil I should buy to do both front and rear (road bike ultegra 8020). I have read various things like the (very long) time need to do complete bleeds and how long oil lasts standing still. There seem to be a multitude of bottle sizes one can buy. I don't mind buying a 1ltr bottle of oil but it would grate a little if I used a fraction and 90% was just laying around doing nothing. Any advice on how much I should buy?

Posts

  • akhakh Posts: 160
    If you make no mistakes and waste none of the oil, the smaller 100ml bottle should be plenty. The filling syringe in the Shimano bleed kit is 35ml for reference. Maybe pick up two 100ml bottles (still cheaper than the litre bottle) just to be safe. I'm sure it'll keep a good few years in an unopened bottle).

    On first fill/bleeding I went through a lot more than 100ml though, largely through my own fault. What's left in the 1 litre bottle doesn't look to have discoloured or deteriorated in any way, but I do keep it in a cupboard in the house (if that makes a difference).
  • david37david37 Posts: 958
    Ok good news, all recent shimano brakes use mineral oil. It is fine to open a bottle, seal it up and come back to it months or even years later. You will find as above that 100ml should be more than enough but if its your first time prepare for some mistakes.

    Also if you're doing a full bleed you might find you have to flush through more than once before you get nice clean fluid. This is especially the case if they haven't been bled for some years as in your case and cr ap has built up.

    It is actually a very straightforward process and not too time consuming IF you've done it a number of times before and know what youre doing, otherwise it can take a while.

    Number 1 tip........ Take your time.

    other tips, remove the brake pads and wheels before touching anything else.
    the screw in the lever for the funnel is very small and the opportunity to damage threads in the lever or the screw or the screws head is high. it requires a light touch to fasten (0.5 to 0.7nm i.e. barely finger tight and less than most torque wrenches even start at).

    Pour a cold drink and go and drink it if you get stressed.

    Put cardboard down under your work area to catch the oil........... you will probably make some mess the first few times you do this.

    Do not use or keep DOT fluid thats been opened. (plus its cheap as chips anyway)
  • veronese68veronese68 Posts: 23,416 Lives Here
    All good advice above, I will add that Shimano mineral oil is the same as LHM used in some cars, like Citroens, but with red dye. That's cheaper, especially if you have a bottle in the garage already.
  • RedClipRedClip Posts: 89
    I use this https://www.amazon.co.uk/Comma-LHM1L-1L-Hydraulic-Fluid/dp/B003BPSVQG
    Current price looks to be £8.05 for 1 litre.
  • slowmartslowmart Posts: 4,039
    Before bleeding zip tie the brake leavers overnight so they are on full brake.

    This should force any air out of the system and negate the bleed but I appreciate you may want to go though the process to build your skills. I did and used a lot more oil than I thought as I needed to flush the system several times. Not a problem, it didn’t go to plan which was one top up.

    There are some wise words above and I’d only add buy more oil than you need. It will always come in for use later if you don’t need it and there is something satisfying about a job which requires attention and you have the parts/ material in stock and to hand.
    “Give a man a fish and feed him for a day. Teach a man to fish and feed him for a lifetime. Teach a man to cycle and he will realize fishing is stupid and boring”

    Desmond Tutu
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