High Compression · GDI Engines

Average Wear
Reference Guide

This page shows standard wear references — useful for a general comparison. But for a personalised result for your exact vehicle, the AI scan gives you a full engine health report in about two minutes.

Click to have your test scanned by AI

Free · Results in ~2 minutes · No tools needed

or scroll down to browse the standard reference charts

It is compression, not direct injection, that moves the color on a newer engine. A high-compression engine builds more cylinder pressure on every stroke, so more combustion gas is pushed past the piston rings and into your sample — even when the engine is barely broken in.

Most high-compression engines are GDI, which is why this has always been called the GDI reference. Use these bands for any high-compression gasoline engine, and read your result against the same mileage range — not against a brand-new engine.

High Compression Reference

The High Compression Engine Guide

Use this reference to see what a healthy high-compression engine looks like at your mileage — then compare your blow-by result against it.

Average Wear

Mileage estimates based on high-compression engines, most of which are GDI.

Two test vials, one deep blue and one teal

0 - 40k Miles

There should be no visible green. A brand new high-compression engine with 0 miles can still pull a teal color — that is the compression, not wear.

40k - 80k Miles

Average wear will start pulling more green color due to gradual cylinder wear however it should be a darker green. A well maintained vehicle can still pull a teal color.

Test vial showing a light lime green result

80k - 120k Miles

Average wear accelerates and will start pulling in the yellows which creates the lighter green color. A well maintained high-compression engine in this range can pull a dark green color.

120k+ Miles

Noticeable wear begins over 120k miles, though well-maintained vehicles may still pull green. Yellow indicates the engine is nearing the end of its life.

*Please refer to our terms and conditions. Test results are provided for informational purposes only and are not a substitute for professional diagnosis, advice, or servicing. Results should be used as a guide in conjunction with other diagnostic methods. We do not assume liability for any decisions, repairs, or outcomes based on the use of this test.