I've been posting on Audi FSI engines for some time now, and have discussed my oil analysis and issues with FSI engine fuel dilution impact on wear and deposit formation. Well, we now have confirmation of the oil-induced deposit formation issues with FSI engines.

Here's a direct quote from an RS4 owner who is also a Mechanical Engineer.





IMO fuel dilution is the root cause for increased volatization and breakdown of the oil. 10 year oil Audi/VW formulations, designed to deal with engine sludge, do not stand up to fuel breakdown and end up as deposits on the valves, combustion chamber and injectors.

Wouldn't it also be smart to trap the oil before it gets to the valves etc. using something like this?

This is for the 2.0l FSI, brand is BSH, from their website:

Details:
Designed with simplicity of install in mind the BSH Bulletproof PCV Stage 2 kit takes our already successful PCV program one step further. Manufactured here in the US, the CNC machined BSH Bulletproof PCV Stage 2 fixes all the major problems associated with the prone to failure PCV system and adds a true catch can to capture all oil vapors that would otherwise make their way back into the engine. This package is the ideal performance solution for those who want the most out of their tuned 2.0T!

This kit comes complete with every hose, bracket, nut, and bolt needed to install!

Function:
Increase your engines performance and longevity with a BSH catch can system. Our catch can catches oil vapors and still fully meets emission requirements. Internally the catch can has chamber that forces oil to separate from the air as it passes through. This oil then falls into the gut of the can and can be drained at your next oil change.

For the best performance possible you do not want this oil making its way back into your engine! Short term oil vapors being ingested result in a greater chance for pre ignition, over time however this oil will cake the intake valves shortening the life of the engine. Outside of oil, the can will also catch water and fuel. Take a look at the detailed pic section to see what muck is getting ingested into your engine! Stop this once and for all!

Thanks for sharing. How is the RLI oils holding up for other members? Is it reducing any of the deposits? It's my understanding that the bio syn oils have exceptional cleaning capability.

saaber1

There is already a cyclonic oil separator in these engines that is a bit more advanced than a catch can. There is nothing more efficient in removing oil from the PVC system that that. But, a cyclonic separator cannot remove volitile oil components that remains in the vapor stage. Fuel dilution can drive flashpoint down in the mid 200F range in these engines, which is the operating oil temperature.

What is the best plan for preventing this? I think it requires attention to oil choice, oil change interval, and fuel additives.

The first two are simple: superior oils and sufficiently short OCIs...whatever those are.

It is the latter that is less clear to me. What additives should be used and at what treat rates? I'm quite sure a constant dosing would be best rather than letting buildup happen then shock-dosing it to clean it up. Some candidate additives are: FP60, RLI's Fuel Additive, Techron or similar products, BG44K, and ester-based two-cycle oil like Maxima K2.

I am experimenting with Maxima K2 in my guinea pig, the VW 1.8T, using it at 750:1 and 500:1 ratios. It is not direct-injected engine but I think it can still provide insight as to relative effectiveness of various fuel additives. It is too early to tell if it will clean the carbon from the piston tops but it certainly did leave the carbon "wet" and able to be easily scraped off.

Prior to using the two-cycle oil, I tried many uses of FP60 and it did NOT clean the carbon from the piston tops. The only hope for it would be for me to increase the treat rate above what's recommended.

I just got done running BG44K in one tankful and I will pull the spark plugs any day now to see what it did. I'll report back what I find.

No one running Biosyn is reporting any misfires or loss in power. This particular owner just bought a 5 gallon pale of Biosyn 5W40 and will be monitoring it's progress by pulling the intake manifold and performing visual inspection of the valves. We'll know after a month on how well it does.

For those who like to read patents, Lubrizol has done some interesting work on creating oil formulations specifically designed to reduce intake valve deposits. In the case of the VW 4 cylinder FSI engine, they show around 40% improvement. One of the key features of the patent is the combination of PAO and synthetic Esters in the oil, with a high percentage of Esters. The one thing they could not patent was RLI's Bio-Ester technology, which was already patented, and uses PAO, bio-ester blends and stabilizers in their formulations.



Method for Reducing Intake Valve Deposits in a Direct Injection Engine

Rl_RS4, are you saying that the cleaning which takes place is from the oil vapors going through the intake valves and combustion chamber? If so, is Biosyn effective because it reduces volatility or because of the cleaning effectiveness of the volatilized oil?

Is the oil volatility inevitable with any oil in this engine and the most important factor in terms of preventing deposits to the intake valves, injectors, etc. the oil's ability to clean?

Very cool info. posted above BTW, thanks!

Yes to all of your questions.

How are Audi service techs cleaning the valves?

RI_RS4 can you post the link to the pictures he is talking about?

best plan for preventing this is to vent crankcase out to atmosphere rather then back into intake. I did this on my S4 and no more oil deposits on the intake side(intercoolers, bypass valves and IM)

second option is to seafoam/water your car twice a year to get rid of the deposits..

first option gets my vote since it eliminates root cause of the problem.

Thanks. Yeah that will work but isn't the loss of having some vacuum in the crankcase (due to PCV suction) a concern that fuel dilution will significantly increase? I've often wanted to install an electric "wet" pump to pull a vacuum out of the crankcase and get rid of the PCV system.

How would you vent to the atm when the PCV is a closed system? Would you just have to run a secondary pump to keep the crankcase under vacuum. Also I will be interested to see how RLI helps with lower deposits.

no need to keep crankcase in vacuum.crankcase with atmospheric pressure is just fine..

you just need to cap of source of crankcase vacuum so you don't have vacuum leak.