Observation – Does Amsoil engine flush actually work? How well can a detergent-based engine flush formula with advanced light base oil technology perform?
Hypothesis – After extensive research, I learned that using a detergent-based engine flush is the safest option available. Many engine flush products on the market are solvent-based or are not listed by the manufacturer. Solvent-based engine flushes are not safe as they could break up deposits in large chunks leading to clogged oil passages, and could also harm engine seals. According to Amsoil their detergent-based engine flush cleans safely at a molecular level allowing the varnish and carbon deposits to become dissolved, suspended, and dispersed within the motor oil after 10 to 15 mins of idling the engine. The deposits are then removed when the oil is drained out during an oil change after the flush. AMSOIL Engine and Transmission Flush contains nothing but potent detergents, making it a more effective cleaner than motor oil.
Experimentation – I performed this Amsoil engine flush test on my 2015 Volvo V60 Polestar with 60,445 miles (97,277 km) The previous owner always had the oil changed on time since new following the Volvo service manual every 10,000 miles (16,000 km) with Volvo-recommended Full Synthetic Castrol Edge Professional at the dealership.
The reason why I performed an engine flush is to have a clean slate inside the engine before I upgrade to AMSOIL Signature Series 100% Synthetic motor oil. This initial clean-up dissolves and disperses sludge, varnish, and deposits in engines. Deposits and sludge are removed instead of being circulated in the new oil. The result is cleaner lubrication and oil filter life is maximized. This is not a mandatory step to do before switching to AMSOIL but the after results indicate that it’s worth doing. If you change to AMSOIL synthetic motor oil without flushing, for example, the detergents in the motor oil will clean accumulated deposits from the engine over subsequent oil changes. When you use AMSOIL Engine Flush, the cleanup is more immediate and helps ensure the engine is clean and free of any accumulated contaminants.
NOTE: Before I performed the engine flush I first changed the engine oil with Castrol Edge Professional and installed a new oil filter to have a proper baseline for this test. This will give us the most accurate after-flush results!
Test Result
I have documented my AMSOIL engine flush results with a perfect visual comparison for anyone who was curious to see a real-world test of how effective AMSOIL engine flush is based on comparing motor oil before and after flushing.
- Brand New Factory Recommended Motor Oil straight out of the bottle – this was the oil I installed after draining the old oil and replacing the filter to have a clean slate to really see how well the engine flush works.
- New Motor Oil after engine flush – this is how the oil looks after performing the Amsoil Engine flush. The new oil that was once golden/amber is now black. Keep in mind, that I captured a small sample of the drained oil for this comparison. When I performed the engine flush I allowed my car to reach operating temperature before I shut the engine off. I poured the engine flush into the oil fill port and started the engine and idled for 15 mins as stated in the product instructions. This is the result.
Conclusion
After seeing how black the motor oil looks after the flush, I would say it definitely worked to remove varnish, and carbon deposits as well! I was also very impressed to see all of the new oil drain out looking completely black and used in just 15 minutes after using AMSOIL Engine flush. I was very shocked to see the results, I couldn’t believe it!
This shows you how important it is to use high quality 100% Synthetic oil because these deposits came from Castrol “Full Synthetic”.
If AMSOIL Signature Series motor oil was used in this engine since new the after flush oil would look the same as the new oil and a flush wouldn’t have been necessary in the first place! This is because AMSOIL is so highly resistant to oxidation and it contains such a high amount of detergents, dispersants. Varnish and carbon wouldn’t have formed and deposited in the first place!
The interesting thing I noticed was it looks like the flush liquified varnish and carbon deposits so well it allowed them to be suspended and dispersed within the oil. It’s also impressive that there are no particles in the used oil that I thought I might see. I had inspected the oil drain pan I used after the oil sat for 2 weeks to see if any sludge or larger particles would settle at the bottom of the drain pan and there was absolutely nothing. This indicates that the deposits were properly suspended in the oil and if there were any tiny particles the oil filter caught them safely.
Keep in mind – Micron Sizes and Engine Wear
We can visually see 40 Micron sized particles with the naked eye.
Particles LARGER than 10 Microns are typically TOO Large to enter clearances.
Particles BETWEEN 1 and 10 Microns are “Micro-grit” which can cause wear.
Particles LESS than 1 Micron are TOO Small to cause wear.
The flush liquifies varnish and carbon particles allowing them to be SAFELY suspended and dispersed within the motor oil not causing wear.
Filter model: HU925/4Y MANN Oil Filter – 99% efficiency at 40 microns
This test result truly indicates that Amsoil’s product overview description is ABSOLUTELY TRUE! Using this engine flush was definitely worth it because it performed extremely well based on how dirty the drained oil looks!
When a company has a long list of performance claims and benefits of their products I know many people might read it and be skeptical at first. This is not the case with AMSOIL. Every product AMSOIL engineers is backed by real-world certified test data and is shared to everyone on their website.
The complete transparency of Amsoil’s testing and product description made me trust their engine flush enough that I personally used it in my extremely rare car to test it for you! I truly believe in only recommending products to people that I can say “yes I have personally tested it myself” if it’s not good enough for me I wouldn’t recommend it to anyone else. This product is absolutely amazing and I say it’s a brilliant product that challenges the beliefs of people who think flushes are pointless or that they don’t work. The best part is once you use AMSOIL 100% Synthetic motor oil you won’t get the deposits other “full synthetic” oils leave behind thanks to AMSOIL’s saturated molecular structure and high resistance to extreme temperatures.
What Causes Carbon Deposits and sludge inside engines?
- Frequent short trips that don’t allow the oil to fully warm up and evaporate moisture
- Ingestion of dirt
- Fuel dilution
- High heat breaking down the oil
As it settles, sludge can clog narrow oil passages or the screen on the oil pickup tube, restricting oil flow to vital parts, especially the upper valve train.
Deposits can cause the rings to stick, reducing engine compression and horsepower.
In my case most of the carbon deposits removed were from the original Castrol Oil being used since new. Since the factory recommended oil is mineral based it breaks down when exposed to the extreme temperatures of the turbocharger and hard driving. When oil breaks down it oxidizes and leaves deposits behind. AMSOIL lubricants resist thinning at high temperatures (high VI) and can suppress the generation of additional friction and heat generated by components in contact due to a thinning lubricant. AMSOIL synthetic lubricants are formulated with base oils that have a saturated molecular structure, meaning oxygen is prevented from attaching. This provides inherent heat and oxidation stability over conventional oils that are unsaturated. Because AMSOIL synthetic oils do not contain contaminants like conventional mineral oils, their base composition does not accelerate oxidation. AMSOIL synthetic lubricants contain oxidation inhibitors that are far better than conventional oils. Oxidation inhibitors are sacrificial in nature, meaning they deplete, or are used over time. Since AMSOIL base oils have better oxidation stability on their own, oxidation inhibitors in AMSOIL synthetic oils last longer because they are not depleted as rapidly. AMSOIL uses a combination of oxidation-inhibitor systems for different temperatures and application needs.
AMSOIL Engine flush most likely removed the deposits around the piston oil control rings. The greatest benefit of removing carbon deposits from the oil control rings is now they can move freely in the piston ring groove and expand on the cylinder running surfaces which could result in improved compression compared to before cleaning. Unfortunately I learned about benefit / possible improvement after I did this test, so I didn’t compression test my engine before and after the flush. I will make a post when I have another car to compression test before and after the flush.
Unfortunately I didn’t take a “before flush picture” of the oil filter housing, but the oil filter housing aluminum surfaces had a dark brown/goldish varnish residue before doing the flush. Now all of that varnish residue is removed as you can see in this picture.
I really regret I didn’t think of taking a before picture but it is what it is now. Clean as new! 🙂 so I’m happy about that.
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