Preventing FSI valve deposits with fuel additive and oil
12-10-2008, 01:12 PM
#1
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Preventing FSI valve deposits with fuel additive and oil
FSI back-side valve deposits are a combination of burnt fuel deposits, due to impurities, and burnt oil deposits, due to oil that volatizes and is recycled through crankcase ventilation, or through evaporation off of the valve guides. As others have mentioned, delivery of cleaning agents through the fuel do not provide a great help with FSI engines, since fuel is injected directly into the cylinder and only minor amounts actually swirl onto the back side of the valves.
Using high detergent, top tier fuels, only solves part of the problem. Top tier fuels have less deposit formation, due to the lower impurities and higher levels of detergents, but they do little to mitigate oil-induced deposit formation. You can help the situation by adding addition fuel additives, to increase the cleaning action in the cylinder head, pistons and rings.
Because of the high amount of fuel that ends up in the oil and dilutes it, in these engines, a significant amount of fuel diluted oil is volatized and burnt off. In fact, the breakdown of oil over time, when mixed with fuel, makes it more volatile and libel to end up as deposits.
This is one of the reasons I was on the bully pulpit talking about oil for so long on this forum. One of my predictions was that RS4 engines would begin to see the same problems with valve deposits that other Audi FSI engines have seen, and attributed only to poor fuel quality.
Oil that is run too long will create excessive deposits. Oil of inferior quality will create excessive deposits. For almost all 502 qualified oils, the working lifetime in an RS4 engine, without degradation leading to increased volatility is between 3K and 5K miles. This degradation can be measured using oil analysis, and was the reason I took the journey to have Terry Dyson work with me to develop a higher performing oil for this Engine.
That is why RLI Biosynthetic SHP 5W-40 oil was born. The oil is designed to withstand high RPMs, fuel dilution, a cam chain that brutal on oil, while maintaining low volatility, low deposit formation, and high lubricity at high operating temperatures. Some of the bio-ester base stock in the oil are specifically good at keeping things clean in a synergistic combination with the PAO bases used in the formulation.
When this is combined with a fuel treatment of RLI BioPlus, which is also a biodegradable fuel additive that is used in every tank, there are some additional synergistic things that happen. Bioplus additives and Biosyn oils have similar chemistry that can better mitigate the stress and degradation caused by fuel dilution of the oil.
I ran Biosyn oil and BioPlus fuel additive in my RS4 with 10K mile OCI's until I sold my car with 40K miles on the clock. In the entire time I owned my car, I had two misfires on startup during cold weather. I now run the oil and fuel additive in my A6 with the V6 FSI engine. No misfires.
IMO if you own an Audi FSI engine, use top tier fuel, and change the oil before it begins to degrade seriously. For my money, with 502 oils, 5K miles is the absolute upper limit. With RLI Biosyn 5W40 7.5 to 10K is the upper limit.
Using high detergent, top tier fuels, only solves part of the problem. Top tier fuels have less deposit formation, due to the lower impurities and higher levels of detergents, but they do little to mitigate oil-induced deposit formation. You can help the situation by adding addition fuel additives, to increase the cleaning action in the cylinder head, pistons and rings.
Because of the high amount of fuel that ends up in the oil and dilutes it, in these engines, a significant amount of fuel diluted oil is volatized and burnt off. In fact, the breakdown of oil over time, when mixed with fuel, makes it more volatile and libel to end up as deposits.
This is one of the reasons I was on the bully pulpit talking about oil for so long on this forum. One of my predictions was that RS4 engines would begin to see the same problems with valve deposits that other Audi FSI engines have seen, and attributed only to poor fuel quality.
Oil that is run too long will create excessive deposits. Oil of inferior quality will create excessive deposits. For almost all 502 qualified oils, the working lifetime in an RS4 engine, without degradation leading to increased volatility is between 3K and 5K miles. This degradation can be measured using oil analysis, and was the reason I took the journey to have Terry Dyson work with me to develop a higher performing oil for this Engine.
That is why RLI Biosynthetic SHP 5W-40 oil was born. The oil is designed to withstand high RPMs, fuel dilution, a cam chain that brutal on oil, while maintaining low volatility, low deposit formation, and high lubricity at high operating temperatures. Some of the bio-ester base stock in the oil are specifically good at keeping things clean in a synergistic combination with the PAO bases used in the formulation.
When this is combined with a fuel treatment of RLI BioPlus, which is also a biodegradable fuel additive that is used in every tank, there are some additional synergistic things that happen. Bioplus additives and Biosyn oils have similar chemistry that can better mitigate the stress and degradation caused by fuel dilution of the oil.
I ran Biosyn oil and BioPlus fuel additive in my RS4 with 10K mile OCI's until I sold my car with 40K miles on the clock. In the entire time I owned my car, I had two misfires on startup during cold weather. I now run the oil and fuel additive in my A6 with the V6 FSI engine. No misfires.
IMO if you own an Audi FSI engine, use top tier fuel, and change the oil before it begins to degrade seriously. For my money, with 502 oils, 5K miles is the absolute upper limit. With RLI Biosyn 5W40 7.5 to 10K is the upper limit.
12-10-2008, 06:50 PM
#3
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Makes sense. I was planning on removing the intake every 5k miles..
to check the valves until I found a oil that didn't crud up the valves. Err, I mean volatize and deposit on the back of the valves.
12-10-2008, 06:54 PM
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Re: Makes sense. I was planning on removing the intake every 5k miles..
Different oil won't affect carbon buildup on valves one way or the other. And 'in tank' fuel additives amount to a spitwad against a battleship for a condition of excessive and early carbon buildup on valves and intake.
That said, it still makes sense to use only high quality oils and fuel additives.
That said, it still makes sense to use only high quality oils and fuel additives.
12-10-2008, 07:57 PM
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I grew up never starting a car if you didn't drive it more than five miles, and always...
running the car hard when possible. Old tales maybe, but all my engines which I fiddled with always looked good on the inside and I still follow this auto-mantra today.
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12-11-2008, 06:37 AM
#9
AudiWorld Super User
Thread Starter
Sure it will
Your statement, "different oil won't affect carbon buildup on the valves one way or the other", is just not factually correct. This is why micro oxidation and TEOST testing is done. These tests were developed because of DI diesel engine deposit issues. The same issues occur with Audi's version of DI.
12-11-2008, 07:05 AM
#10
AudiWorld Expert
What about running a can of BG 44K in a tank? And Dyson has a formula he recommends to be used?
Your thoughts.
I am thinking of switching to that oil but worry about the warranty issue like cit1991 mentioned
I am thinking of switching to that oil but worry about the warranty issue like cit1991 mentioned