Magura MT7 flush with Blue Blood while upgrading to XTR M9220

[JordanHudson83]

Hey Greg,
Can you help me do a flush with Magura mt7 calipers using blue blood, while pushing Shimano LV (orange) fluid to XTR M9220? I was going to cut the cable and push all the blue blood out the hose but didn’t want to mix fluid since the Shimano is lower viscosity. Thanks in advance for any advice.

Jordan

 

[Greg Watts]

Hey Greg, Can you help me do a flush with Magura mt7 calipers using blue blood, while pushing Shimano LV (orange) fluid to XTR M9220? I was going to cut the cable and push all the blue blood out the hose but didn’t want to mix fluid since the Shimano is lower viscosity. Thanks in advance for any adv...

Right, let's untangle this - because your instinct is correct, even if the terminology's making it sound more complicated than it is. Short answer: yes, keep them completely separate - never let Blue Blood and Shimano fluid touch, in any dilution, on any tool.

Magura MT7 (Blue Blood): This one's the easy bit. A flush is just pushing fresh Blue Blood through from the caliper syringe until clean fluid runs out the lever side, cycling back and forth to chase bubbles - that's the standard method however you're doing it. There's no viscosity conflict to worry about here at all, because Blue Blood is the only fluid Magura's system is ever meant to see.

XTR M9220 (Shimano LV): The M9220 was specifically designed around Shimano's new Low Viscosity oil - it's built with different seals to suit it, so LV is the only fluid that's validated for that brake. Critically, that's not just "vs Magura" - Shimano's own line is that do not mix SHIMANO hydraulic mineral oil with SHIMANO low viscosity oil, as failure to do so may prevent the brakes from operating and result in serious injury.

So even standard Shimano red mineral oil is off-limits in an M9220 - it has to be LV, full stop. The actual risk in your plan:

The danger isn't the two systems somehow mixing in use - they're sealed, separate hydraulic circuits with zero shared plumbing. The danger is cross-contamination via shared kit: if you push Blue Blood through with a syringe, then reuse that same syringe/funnel/hose for the LV job without a proper clean, you'll get exactly the trace contamination Shimano warns about. So:

• Use a dedicated syringe/hose set for the Magura job, and a completely separate, dry set for the Shimano job • Don't "top up" one with leftover fluid from the other, even a few drops

• If you only own one bleed kit, strip and thoroughly flush it with isopropyl alcohol and let it dry fully between jobs

You're not overthinking this, by the way - treating Blue Blood and Shimano LV as two fluids that must never meet is exactly right, not overcautious.

 

[JordanHudson83]

Right, let's untangle this - because your instinct is correct, even if the terminology's making it sound more complicated than it is. Short answer: yes, keep them completely separate - never let Blue Blood and Shimano fluid touch, in any dilution, on any tool.

Magura MT7 (Blue Blood): This one's the easy bit. A flush is just pushing fresh Blue Blood through from the caliper syringe until clean fluid runs out the lever side, cycling back and forth to chase bubbles - that's the standard method however you're doing it. There's no viscosity conflict to worry about here at all, because Blue Blood is the only fluid Magura's system is ever meant to see.

XTR M9220 (Shimano LV): The M9220 was specifically designed around Shimano's new Low Viscosity oil - it's built with different seals to suit it, so LV is the only fluid that's validated for that brake. Critically, that's not just "vs Magura" - Shimano's own line is that do not mix SHIMANO hydraulic mineral oil with SHIMANO low viscosity oil, as failure to do so may prevent the brakes from operating and result in serious injury.

So even standard Shimano red mineral oil is off-limits in an M9220 - it has to be LV, full stop. The actual risk in your plan:

The danger isn't the two systems somehow mixing in use - they're sealed, separate hydraulic circuits with zero shared plumbing. The danger is cross-contamination via shared kit: if you push Blue Blood through with a syringe, then reuse that same syringe/funnel/hose for the LV job without a proper clean, you'll get exactly the trace contamination Shimano warns about. So:

• Use a dedicated syringe/hose set for the Magura job, and a completely separate, dry set for the Shimano job • Don't "top up" one with leftover fluid from the other, even a few drops

• If you only own one bleed kit, strip and thoroughly flush it with isopropyl alcohol and let it dry fully between jobs

You're not overthinking this, by the way - treating Blue Blood and Shimano LV as two fluids that must never meet is exactly right, not overcautious.

So I’ll need to buy a new hose? I shouldn’t use the hose that I have currently with blue blood. I apologize if I’m missing something I just don’t want to jack it up haha

 

[Greg Watts]

So I’ll need to buy a new hose? I shouldn’t use the hose that I have currently with blue blood. I apologize if I’m missing something I just don’t want to jack it up haha

No apology needed, Jordan - this is exactly the right question to ask before you start cutting things.

Good news: you don't need to go shopping specially. The hose is Shimano-specific and comes fitted to the M9220 kit already - Shimano hose barbs/olives and Magura's banjo fittings aren't interchangeable anyway, so there was never a version of this job where the old MT7 hose could carry over to the new brake. Different fitting standard, different hose, full stop - nothing to do with the fluid.

So the old Blue Blood-filled hose from the MT7 just gets binned (or kept as a spare bleed hose for future Magura jobs, if you want) - it's not something you flush and reuse on the Shimano side. The confusion in my last post was really about bleed kit hygiene (syringe, funnel, bleed block) if you're using the same tools for both jobs - the actual brake hose itself was never shareable between the two systems regardless.

One more thing worth double-checking before you start: the M9220 hose usually comes pre-cut long for trimming to your frame, so you'll be doing the "cut to length, thread through internal routing" job on the new hose, not the old one. If your frame's internally routed and fiddly, some people do use the old dead hose (once fully drained, no fluid left in it) taped to the new one as a pull-through to fish it past frame guides - that's fine, it's just acting as string at that point, no fluid contact involved.

 

[JordanHudson83]

No apology needed, Jordan - this is exactly the right question to ask before you start cutting things.

Good news: you don't need to go shopping specially. The hose is Shimano-specific and comes fitted to the M9220 kit already - Shimano hose barbs/olives and Magura's banjo fittings aren't interchangeable anyway, so there was never a version of this job where the old MT7 hose could carry over to the new brake. Different fitting standard, different hose, full stop - nothing to do with the fluid.

So the old Blue Blood-filled hose from the MT7 just gets binned (or kept as a spare bleed hose for future Magura jobs, if you want) - it's not something you flush and reuse on the Shimano side. The confusion in my last post was really about bleed kit hygiene (syringe, funnel, bleed block) if you're using the same tools for both jobs - the actual brake hose itself was never shareable between the two systems regardless.

One more thing worth double-checking before you start: the M9220 hose usually comes pre-cut long for trimming to your frame, so you'll be doing the "cut to length, thread through internal routing" job on the new hose, not the old one. If your frame's internally routed and fiddly, some people do use the old dead hose (once fully drained, no fluid left in it) taped to the new one as a pull-through to fish it past frame guides - that's fine, it's just acting as string at that point, no fluid contact involved.

Thank you! I really appreciate all your help, the bike shop unfortunately didn’t know this.

 

[Greg Watts]

Thank you! I really appreciate all your help, the bike shop unfortunately didn’t know this.

No worries, Jordan - glad it helped. Bike shops are usually solid on this stuff, but "don't let the Magura and Shimano fluids so much as look at each other" is a fairly niche crossover job, so I won't hold it against them.

Good luck with the bleed - if the M9220 lever feels a bit soft or spongy on the first bite after install, that's just air working its way out, give it another cycle through before you panic. Shout if anything looks odd once it's apart.