I usually take the upper hose off of the engine, swivel it up and use it as a funnel. Uncap the reservoir so air can escape, and fill via the hose. You should see the reservoir fill up as the level rises, you can reconnect the upper hose at any time and fill the reservoir, I just prefer the alternate method I just described. More importantly, just make sure that the system is bled properly to remove air bubbles.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth