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Before I start, I know. “Additives are a waste of money.” “Search posts.” I have been watching some videos, reading posts, etc. the one video that got me rethinking it was by a gentleman named Scotty Kilmer. Look him up on YouTube. Some great knowledge. Now to my question. I have a 2008 Eos. About 150000 miles on it. Bought used two years ago. I’ve done a lot of repairs myself with the help of my cousin who’s a mechanic. Fixed all oil leaks coolant leaks etc. Is there anything anyone here recommends to add to your gas tank such as Amsoil, or something to add to engine oil to clean deposits from the pistons, etc before performing an oil change? Suggestions only please.
 

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I've read the 'Snake Oil' posts too. I had a particular issue with a gas engine Cat converter which was a marginal fail when they did an annual emissions test. I was sceptical when the tester suggested a bottle of (Winns I think?) in a 1/4 full gas tank then run the car in a higher gear at 3K rpm for a while on a cruise. I took the car back and the emissions levels were way down.

These additives work by raising the combustion temperature, which helps to burn off carbon. It won't do much on the inlet side though, but good for injectors, valves and Cat.

The active ingredient was Xylene (Xylol) plus other 'secret' ingredients. Xylene is commonly used as a varnish thinner. I bought a gallon and put some of that in. Also used it in my diesel as well. But I'm not recommending it to others and it's your risk!
 

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I've heard a lot of good things about Liquid Moly engine flush. It's used before an oil change and can help clean out a lot of sludge in the engine. Never personally tried myself, the thing that always stops me from trying is a very rare chance that the flush may release a lot of garbage in the engine and then clog the oil channels which can be a catastrophe, or choke up the catalytic converters. Quite unlikely I think, though.
 

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The OP was asking about additives for the gas tank.
Previously when dyno engine oils and engines were in early development, additives such as the 'Moly' products were commonly used in engine oils because of the benefits of graphite coatings to reduce bearing and piston friction.

Engine design and manufacturing tolerances have reduced for longer engine life and turbos became common. Car manufacturers realised engine oils needed to be designed for their newer engines and V.W established their own oil specification codes, initially for their own (expensive) dealer brand oils. Now V.W oil specifications are available to motor oil manufacturers who can specify them with their brand. The second big oil change was the move from Dyno to Synthetic with wider viscosity ranges, Thinner oil gets around more with less drag and improves efficiency. These are big changes which an additive just won't match. Serious engine failure or shortend life caused by lubrication oil is unusual on modern engines and those failures or wear that can occur e.g on some camshafts, can be attributed to their design. An EOS roof is more likely to fail and write off your car, or you crash it, before the engine wears out!

If V.W have done their own research on oil specs for longevity and performance in their engines, IMHO I see no point in adding something else to engine oil, unless it is considerably superior to V.W recommended specs?

A CAT or DPF keeping your car off the road when it fails emissions tests, is a big expensive problem if either have to be replaced.
 

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Bact what Vox said earlier…. By far the biggest deposit issue with these engines will be with the intake valves. Direct injection engines like ours are prone to getting heavy intake track deposits whose root cause lies with the crankcase ventilation system. With no fuel to wash off the the intake valves, oil deposits just get baked onto the valves and intake channels. No gas tank additive is going to touch that mess. You may see some deposits get burned off the pistons, but those are minor compared to the intake track. If you want to really clean things up you need to remove the intake manifold and clean up the intake valves. There are solvent based methods to do that, but the best is probably to blast them with ground walnut shells.

The best “system” I’ve read about is one that I believe BMW dealers use. It utilizes a special plate that blanks off the intake channel with a port for the blasting gun. They attach the plate, the rotate the engine until the intake valve is closed. The next step is to blast the intake valve, followed by vacuuming out the debris. It takes minutes per cylinder and read to be fairly “mess free.”
 
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Been there with a diesel and clogged EGR. Closed loop emissions systems put loads of junk and oil gunge into the input side. I read about the bead blast technique to avoid removing the manifold, but it doesn't seem common in UK? I got as far as removing the plastic inlet manifold to clean up as much as I could, but couldn't get around the inlet valves which bead blasting would have done.

The problem exists with the design of modern engines. They sit low in the engine bay and the PCV valve and low height valve cover isn't that good at removing oil compared to a decent old style Venturi oil catch can.
 

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Been there with a diesel and clogged EGR. Closed loop emissions systems put loads of junk and oil gunge into the input side. I read about the bead blast technique to avoid removing the manifold, but it doesn't seem common in UK? I got as far as removing the plastic inlet manifold to clean up as much as I could, but couldn't get around the inlet valves which bead blasting would have done.

The problem exists with the design of modern engines. They sit low in the engine bay and the PCV valve and low height valve cover isn't that good at removing oil compared to a decent old style Venturi oil catch can.
The OP was asking about additives for the gas tank.
 

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Hi

All good info . I've used bg44k and techron once a year before sn oil change . My research suggested that to have the greatest effect the addative needs to contain PEA.

The above do seem to be at the expensive end of the range.

Hard to verify the results but year emissions test seems fine

Regards

Sent from my SM-A526B using Tapatalk
 
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