I was discussing whether going up In viscosity in the later EA888 2.0T in Tiguans. They are calling for 0w20 Vw 508.00 so many Tiguans have oil burning issues. I think vw 504.00 would be better or even 502.00 since the early levering of this motor used 5w40.
The other poster states all these reasons why 0w20 is the better choice. Do you agree?
While fuel economy was a goal, engineers didn't just put thin oil in an old engine. They redesigned the hydraulics and clearances of the Gen 3B to rely on the flow characteristics of 0W-20 (VW 508.00).
Here are the specific mechanical changes from the older EA888 (Gen 1/2) to your Gen 3B that necessitate—and protect—the use of 0W-20.
1. The Variable Displacement Oil Pump (The "Flow" Argument)
This is the most critical mechanical difference.
• Old Gen 1/2: Used a fixed-volume or simplified regulated pump. Higher RPM = Higher Pressure. Thick oil (5W-40) worked fine because the pump just brute-forced it through.
• Gen 3B Design: Uses a fully variable vane pump controlled by the ECU. It targets specific Flow Volumes, not just pressure.
• The Physics of 508.00: The pump is calibrated for the viscosity of 0W-20.
• If you use 5W-40: The thicker fluid creates higher resistance (pressure) immediately. The pump detects this "high pressure" and retracts the vanes to lower the output.
• The Result: You actually get LESS OIL FLOW (volume) across the bearings with 5W-40 because the pump is trying to compensate for the high pressure.
• Why 0W-20 wins: It flows freely, allowing the pump to keep the vanes open, flooding the bearings with high-volume cooling flow rather than just high-pressure static fluid.
2. The "Budack Cycle" Combustion (Thermal Management)
The "B" in Gen 3B stands for the Budack Cycle. This is why your engine runs cooler than a GTI engine.
• The Design: The intake valves close early (before the piston reaches the bottom on the intake stroke).
• The Effect: This lowers the "effective" compression ratio, which significantly lowers the Peak Combustion Temperature.
• The Oil Link: Because the combustion process itself is cooler than a standard Otto cycle engine, the oil is subjected to less thermal stress. This allows the lower HTHS (High Temperature High Shear) rating of 0W-20 (2.6 mPas) to survive where it might fail in a hotter running Gen 2 engine.
3. Tighter Bearing Clearances & Micro-Finishing
• Main & Rod Bearings: The Gen 3B uses tighter bearing clearances than previous generations.
• The Mechanism: A tighter gap requires a thinner fluid to enter and establish a wedge quickly, especially on cold starts.
• The Risk: 5W-40 is too thick to enter these tight clearances instantly upon startup (where 90% of wear occurs). 0W-20 penetrates immediately.
4. The Piston Ring Pack (Low Tension)
• The Change: As already mentioned the rings have lower spring tension to reduce friction.
• The Oil Link: A thick 5W-40 oil film can actually be too thick for these low-tension oil control rings to scrape effectively, leading to more oil consumption (the ring "hydroplanes" over the oil rather than scraping it).
• 508.00 Spec: The 0W-20 is designed to break surface tension easily, allowing the low-tension rings to scrape the cylinder wall clean.
5. The Chemistry of VW 508.00 (It's not just "thin oil")
• Zirconium Marker: VW 508.00 oil contains Zirconium as a chemical marker (and is dyed green). This isn't just for looks; it's to verify the correct additive package is present.
• No Calcium: 508.00 formulas (like your Liqui Moly 6200) often reduce Calcium detergents (which cause LSPI/Knock) and replace them with Magnesium. Old school 502.00 5W-40s are often high-calcium, which promotes Low Speed Pre-Ignition in these engines.
The other poster states all these reasons why 0w20 is the better choice. Do you agree?
While fuel economy was a goal, engineers didn't just put thin oil in an old engine. They redesigned the hydraulics and clearances of the Gen 3B to rely on the flow characteristics of 0W-20 (VW 508.00).
Here are the specific mechanical changes from the older EA888 (Gen 1/2) to your Gen 3B that necessitate—and protect—the use of 0W-20.
1. The Variable Displacement Oil Pump (The "Flow" Argument)
This is the most critical mechanical difference.
• Old Gen 1/2: Used a fixed-volume or simplified regulated pump. Higher RPM = Higher Pressure. Thick oil (5W-40) worked fine because the pump just brute-forced it through.
• Gen 3B Design: Uses a fully variable vane pump controlled by the ECU. It targets specific Flow Volumes, not just pressure.
• The Physics of 508.00: The pump is calibrated for the viscosity of 0W-20.
• If you use 5W-40: The thicker fluid creates higher resistance (pressure) immediately. The pump detects this "high pressure" and retracts the vanes to lower the output.
• The Result: You actually get LESS OIL FLOW (volume) across the bearings with 5W-40 because the pump is trying to compensate for the high pressure.
• Why 0W-20 wins: It flows freely, allowing the pump to keep the vanes open, flooding the bearings with high-volume cooling flow rather than just high-pressure static fluid.
2. The "Budack Cycle" Combustion (Thermal Management)
The "B" in Gen 3B stands for the Budack Cycle. This is why your engine runs cooler than a GTI engine.
• The Design: The intake valves close early (before the piston reaches the bottom on the intake stroke).
• The Effect: This lowers the "effective" compression ratio, which significantly lowers the Peak Combustion Temperature.
• The Oil Link: Because the combustion process itself is cooler than a standard Otto cycle engine, the oil is subjected to less thermal stress. This allows the lower HTHS (High Temperature High Shear) rating of 0W-20 (2.6 mPas) to survive where it might fail in a hotter running Gen 2 engine.
3. Tighter Bearing Clearances & Micro-Finishing
• Main & Rod Bearings: The Gen 3B uses tighter bearing clearances than previous generations.
• The Mechanism: A tighter gap requires a thinner fluid to enter and establish a wedge quickly, especially on cold starts.
• The Risk: 5W-40 is too thick to enter these tight clearances instantly upon startup (where 90% of wear occurs). 0W-20 penetrates immediately.
4. The Piston Ring Pack (Low Tension)
• The Change: As already mentioned the rings have lower spring tension to reduce friction.
• The Oil Link: A thick 5W-40 oil film can actually be too thick for these low-tension oil control rings to scrape effectively, leading to more oil consumption (the ring "hydroplanes" over the oil rather than scraping it).
• 508.00 Spec: The 0W-20 is designed to break surface tension easily, allowing the low-tension rings to scrape the cylinder wall clean.
5. The Chemistry of VW 508.00 (It's not just "thin oil")
• Zirconium Marker: VW 508.00 oil contains Zirconium as a chemical marker (and is dyed green). This isn't just for looks; it's to verify the correct additive package is present.
• No Calcium: 508.00 formulas (like your Liqui Moly 6200) often reduce Calcium detergents (which cause LSPI/Knock) and replace them with Magnesium. Old school 502.00 5W-40s are often high-calcium, which promotes Low Speed Pre-Ignition in these engines.
