Supertech B58 5mm Intake Valve Stem Oil Seal (VSI-BM50-I) - Inlet/Valve Guide Seal for BMW 3.0 Turbo Six M140i M240i 340i 440i 540i 640i 740i 840i X3/X4 M40i X5/X6/X7 40i Z4 M40i & Toyota GR Supra A90 A91

Supertech VSI-BM50-I 5 mm inlet valve stem oil seal for B58 applications. A high quality valve guide oil seal designed for the BMW and Toyota 3.0 turbo straight-six, delivering tight, consistent sealing on 5 mm inlet stems across daily-driven, tuned and track-focused builds.

Why this Supertech seal is a smart upgrade

• Accurate 5 mm fitment for B58B30 inlet valves to keep oil where it should be.
• Helps minimise oil usage and reduce blue smoke on cold start by improving stem-to-guide control.
• Supports clean intake tracts and intercooler systems by limiting oil mist past the guides.
• Great during top-end service, head overhauls, camshaft work or when pairing with uprated valve springs.
• Proven durability for fast road, mapped and track-day cars.

We use these on our own builds and customer cars with excellent results. Feedback is consistently positive for reliability, fit and long-term sealing performance.

Vehicle fitment

For models running the B58 3.0 straight-six, including:

• BMW M140i
• BMW M240i
• BMW 340i and M340i
• BMW 440i and M440i
• BMW 540i
• BMW 640i
• BMW 740i
• BMW 840i
• BMW X3 M40i
• BMW X4 M40i
• BMW X5 40i
• BMW X6 40i
• BMW X7 40i
• BMW Z4 M40i
• Toyota GR Supra A90 and A91 3.0

If you would like us to confirm compatibility for your exact year or chassis code, get in touch and we will be happy to help.

What you receive

• 1 x Supertech 5 mm inlet valve stem oil seal

Part number

VSI-BM50-I

Brand

Supertech

Professional fitting

For expert fitting and head work, book with MJ Modifications in Warwickshire. Request a quote: info@mjmodifications.co.uk.

Why buy from MJ Modifications

• Tested in-house on B58 shop cars and customer builds.
• Honest advice from enthusiasts who build, drive and maintain these engines.

Search terms to help you find the right part

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