Torx, E-Torx and XZN: Which Bit Goes Where on VW, Audi and BMW

29. Oktober 2026

34-piece Torx and E-Torx bit socket set in case

Most stripped fasteners on European cars come from one mistake: the wrong star-shaped tool in the right-looking hole. Torx, external Torx (E-Torx) and XZN triple square look similar at a glance, but they are three different drive shapes and they are not interchangeable. This guide shows how to tell them apart, where each turns up, and how to avoid rounding out a bolt you needed to reuse.

The Three Drives

Drive	Shape	Tool
Torx (internal, "star")	Six-lobed recess in the fastener head	T-size bit or driver, sizes like T25, T30, T40
E-Torx (external Torx, "E-star")	The same six-lobed shape but on the outside of the head or nut, like a hex bolt with lobes	Female E-size socket, sizes like E10, E12, E14
XZN (triple square, 12-point spline)	Twelve flat-sided points, like three overlapping squares, in the head recess	Male XZN bit or socket, sized in millimeters

E-sizes and T-sizes are separate numbering systems. An E-size does not equal the same T-size number, so never guess a socket by its number. Fit it and look.

The Mix-Up That Strips Bolts

A Torx bit will often slide partway into an XZN recess. It feels close enough. Under torque it slips and chews the corners, and now the bolt is a problem. Sources we checked are blunt about this: the wrong profile damages the head.

Likewise, a 12-point spline or a plain hex-style tool is not the same as a true triple square. XZN points are spaced at 90-degree angles in a specific pattern, and generic spline tools can fit loosely.

How to Tell What You Have

Clean the head. Dirt, undercoating and rust hide the shape.
Look at where the shape is. Lobes on the outside of a head or nut mean E-Torx. A recess means Torx or XZN.
Count the points in a recess. Six rounded lobes is Torx. Twelve flat-sided points is XZN.
Check for a pin in the center of the recess. That is a tamper-resistant Torx and needs a bit with a hole in the tip.
Dry-fit the tool. It should seat fully with no rocking. If it rocks, it is the wrong drive or size.

Where You Will See Them, By Brand

We only list uses that more than one source confirmed. Your car may differ by model and year, so treat this as a guide, not a fitment chart.

Brand	Confirmed use	Drive
VW / Audi	CV axle inner joint bolts (confirmed on an Audi B6/B7 S4 owner thread and a genuine VW parts listing)	XZN triple square
BMW	Widely used across 3 Series chassis: subframe, suspension, seat rails, cylinder head bolts on many engines	E-Torx
BMW	XZN is reported as uncommon on older 3 Series	XZN

We did not find two independent sources for Mercedes, Porsche, Skoda or SEAT specifics, so we are not listing them. Look at the fastener itself and follow your service manual.

Tools You'll Need

Female E-Star (E-Torx) Socket Set, E4 to E24 - for external-lobed bolts and nuts
34-Piece Torx Bit and E-Torx Socket Set - male Torx bits plus female E-Torx sockets in one case
5-Piece Torx Bit Set, T15 to T40 - the common internal Torx sizes
Impact Torx Bit Set, S2 steel - for use with impact tools

Note on XZN: Wrench Haus does not sell XZN triple square sockets. XZN is a separate tool, and our Torx and E-Torx sets do not cover it. If you have VW or Audi CV axle bolts to remove, buy a proper triple square set.

Step 1: Clean and Expose the Fastener

Pick out dirt and rust from the recess with a pick or small screwdriver and brush it clean. A packed recess stops the bit seating fully, and a bit that is not fully seated is what rounds a bolt.

Step 2: Identify the Drive and Size

Use the checklist above. Pick the tool that matches the shape, then test-fit it before applying force. Some guides suggest tapping the bit in with a hammer to make sure it is fully seated, which helps on rusty bolts.

Step 3: Seat Fully and Keep It Square

Push the bit all the way in and keep the tool in line with the bolt. Use a short extension where you can, since long extensions flex and let the bit walk. For hard-to-break bolts, apply a sharp, steady pull rather than a slow, gradual one, and use penetrating oil in advance.

Step 4: Hand Tool or Impact?

Use a hand tool to break a bolt loose if you are unsure of the fit, since you feel slippage before it does damage. If you use an impact tool, use bits made for it, like the impact set above, and only once you are sure the fit is right. Never hammer a doubtful fit with an impact.

Step 5: Do Not Substitute 6-Point or 12-Point Tools

Match the tool to the head. E-Torx wants an E-Torx socket, not a hex socket or a 12-point spline. An XZN bolt needs a true triple square, which has twelve points at specific 90-degree angles. A generic spline bit can fit loosely and strip it. Pick tool style by drive shape, not by what is closest in the drawer.

Step 6: Reinstall Correctly

Replace any fasteners your manual calls for replacing, and torque to the value in your service manual. We do not list numbers here because they vary by car, engine and bolt.

Tamper-Resistant Torx

Security Torx has a pin in the center. Use a bit with a matching hole. If you do not have one, do not force a standard bit; you will damage the pin or the lobes.

Common Mistakes

Using Torx in an XZN bolt. It fits loosely and strips.
Guessing sizes by number. E and T sizes are different systems.
Not cleaning the recess. The bit sits half in and rounds the bolt.
Using a doubtful fit with an impact. Hand tool first.
Skipping penetrating oil on old, rusty hardware.

If It's Already Stripped

Stop, and read our guide on how to extract a stripped or broken bolt before you make it worse.

Frequently Asked Questions

What is the difference between Torx, E-Torx and XZN?

Torx is a six-lobed recess in the fastener head. E-Torx has the same six-lobed shape on the outside of the head or nut and takes a female E-size socket. XZN, or triple square, is a recess with twelve flat-sided points and takes a male bit sized in millimeters. They are three different drives and are not interchangeable.

Can I use a Torx bit in a triple square bolt?

No. A Torx bit will often slide partway into an XZN recess and feel close enough, but under torque it slips and chews the corners. A generic 12-point spline tool can also fit loosely. An XZN bolt needs a true triple square tool. Count the points: six rounded lobes is Torx, twelve flat-sided points is XZN.

Is an E10 socket the same as a T10 bit?

No. E-sizes and T-sizes are separate numbering systems, and an E-size does not equal the same T-size number. Never guess a socket by its number. Dry-fit the tool instead: it should seat fully with no rocking, and if it rocks, it is the wrong drive or size.

What bolts on a VW or Audi use triple square?

This guide confirms XZN triple square on VW and Audi CV axle inner joint bolts, verified on an Audi B6/B7 S4 owner thread and a genuine VW parts listing. Models and years vary, so look at the fastener itself and follow your service manual. Note that Wrench Haus Torx and E-Torx sets do not cover XZN.