I measure the results on cleaning, deposits, compression and noise before and after running the cleaning cycle of Liqui Moly’s Proline Engine Flush on my gasoline, 2.0 litre turbocharged Audi A4.

Featured Product or Tools
Liqui Moly Engine Flush https://geni.us/liquimolyengineflush (Amazon)
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Mity Vac Compression Tester Kit https://geni.us/mityvaccompression (Amazon)
Bentley Publishers Audi A4 B6B7 Service Manual https://geni.us/bentleyaudia4manual (Amazon)
Haynes Repair Manual Audi A4 0208 https://geni.us/haynesaudia4manual (Amazon)

Chapters
0:00 Product and test category intro
4:51 Baseline tests
13:36 Installing new parts
15:28 Cycling the engine cleaner
15:57 Second set of performance tests
17:44 The results

I start with baseline figures of the car’s decibel readings at idle from an exterior and interior location, then take a sample of the current oil and filter it to look for deposits that might be floating around the oil pan. I take a good look under the valve cover for cleanliness in the head, then take dry and wet compression readings from all cylinders as well as inspecting the cylinder condition with a borescope.

Then I clean, and do it all over again! I try to be as critical and objective of the marketed benefits of Engine Flush as possible to avoid the hype of cleaning effectiveness based on disposed oil samples alone.

It’s entirely possible that Liqui Moly’s Proline Engine Flush DID clear out tight passages that assisted cylinder #4 into operating at peak current performance.