2023-2024 Audi Engine Coolant Mixing Guidelines

Audi has issued Technical Service Bulletin (TSB) 2025303/14 to provide comprehensive guidelines on identifying and mixing factory-fill engine coolants. This bulletin, which supersedes TSB Group 19 number 22-28 dated January 28, 2022, is essential for maintaining the integrity of your Audi's cooling system, especially concerning proper Audi engine coolant mixing.

Technical Background

Modern combustion engines place higher demands on their cooling systems, requiring advanced coolants. Audi has continuously developed its coolant formulations to meet these evolving requirements. The TSB outlines the evolution of Audi's approved engine coolants over the years.

Evolution of Audi Engine Coolants

Audi has introduced several generations of engine coolants, each designed to offer improved performance and protection. Understanding these types is crucial for proper maintenance and Audi engine coolant mixing.

• G11, G12, and G12+ coolants: These older formulations have been replaced by improved versions.
• G12++ coolant: Introduced in Model Year (MY) 2005, this coolant became available for service in all engines.
• G13 coolant: Starting from MY 2008, G13 was used as the initial fill and service coolant.
• G12evo coolant: Introduced in MY19, G12evo also serves as the initial fill and service coolant.

It's important to note that Audi is one of the few manufacturers whose coolant does not typically require changing, emphasizing the need for correct coolant types and proper handling.

Understanding Coolant Mixing Compatibility

This TSB provides a detailed chart to determine which service coolants can be added to the factory-filled coolant. Improper Audi engine coolant mixing can lead to reduced corrosion protection.

To use the compatibility chart:

1. Identify the coolant additive currently in your cooling system, often by its color (G11 green-blue, G12 red, G12+ red, G12++ violet, G12evo violet, G13 purple).
2. Locate your current coolant in the upper horizontal row of the chart.
3. Refer to the vertical column on the left to see which coolants can be mixed.

Can be mixed with:	Green-blue G11 (≥ 1994)	Red G12 (≥ 1996)	Purple G12+ (≥ 2000)	Purple G12++ (≥ 2005)	Purple G13 (≥ 2012)	Purple G12evo (≥ 2018)
G11	Green	Red	Red	Red	Red	Red
G12	Red	Green	Yellow	Yellow	Yellow	Yellow
G12+	Red	Yellow	Green	Yellow	Yellow	Yellow
G12++	Red	Yellow	Yellow	Green	Green	Green
G13	Red	Yellow	Yellow	Green	Green	Green
G12evo	Red	Yellow	Yellow	Green	Green	Green

Color Key for Mixing:

• Green: Can be mixed in any ratio.
• Yellow: Mixing is possible, but it will cause a reduction in corrosion protection.
• Red: Cannot be mixed.

While coolants can be mixed as indicated, it is always best practice to change the coolant entirely if mixing incompatible types, due to the risk of reduced corrosion protection. G12++ and G13 are fully compatible with each other.

Important Warnings and Best Practices

Several critical warnings are highlighted in the TSB to ensure proper cooling system maintenance and prevent damage.

• Deionized water must not be used. Only mix distilled water with coolant additives as per ElsaPro procedures.
• Drained coolant must not be reused.
• If G11 is mixed with G12+, G12++, G13, or G12evo, the coolant will turn brown, which is considered normal.
• For MY2015 Audi A3 2.0TDI models with engine code CRUA, G13 must still be used. Only G12evo can be used in the Audi e-tron.
• If a cooling system issue necessitates a coolant change, the system should be drained using ElsaPro procedures, refilled with water, and the engine run for 15 minutes with the heater on to remove residual coolant. The final step is to drain and fill the system to the freeze protection ratio specified in ElsaPro.

Required Tools and Parts

When working with Audi coolants, specific tools and part numbers are referenced:

• G12evo part number: Ready-to-use G-12E-050-1G-DSP.
• Refractor T10007B or T10007A/B: Used to read the freeze protection of coolants, specifically the G12++ scale for G12evo coolant and the G13 scale for G12/G13 mixtures.

Warranty Information

Audi states that cooling system drain and fill procedures due to coolant mixing or the use of incorrect coolant are not covered by Warranty. This TSB is informational and does not apply to any Audi warranty claims related to these issues.

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Source: NHTSA ID: 10233771