Testing the Gasoline Dilution Rate of Gasoline in Engine Oil in Accordance with ASTM D3525 and Japan Petroleum Institute Standard JPI-5S-24

Importance of the Topic

Gasoline contamination reduces engine oil viscosity impairing lubrication and accelerating wear.
Monitoring fuel dilution rate enables informed maintenance and protects engine health.

Objectives and Study Overview

The study demonstrates a gas chromatographic method for quantifying gasoline dilution in engine oil in compliance with ASTM D3525 and JPI-5S-24 standards. Analysis leverages a Shimadzu Nexis GC 2030 AF system under standardized conditions.

Methodology and Instrumentation

The gas chromatographic protocol uses an SH Rtx 1 column (5 m 0.1 mm 0.1 um). Oven program starts at 50 C holds then ramps to 290 C at 45 C per minute. Injection at 255 C with split ratio 1 5. Detector is FID at 300 C. Carrier gas nitrogen at 15 mL per minute with 3 mL per minute purge. Samples consist of 1 g engine oil spiked with known mass of n C14 as internal standard. No solvent dilution is required. Column resolution between n C14 and n C16 is verified.

Instrumentation Used

• Shimadzu Nexis GC 2030 AF with AOC 20i autosampler
• SH Rtx 1 capillary column 5 m 0.1 mm ID 0.1 um film thickness
• Flame ionization detector
• Nitrogen carrier gas in constant linear velocity mode

Main Results and Discussion

Repeatability tests (n 10) at 0.5 5.0 and 10.0 mass percent gasoline dilution yielded relative standard deviations below 1.1 percent. Column resolution of 7.3 between n C14 and n C16 meets USP criteria of 3 to 8. Accuracy aligns with specified tolerances in ASTM and JPI standards.

Benefits and Practical Application

• Direct analysis without pretreatment or solvent dilution
• Compliance with international standards for routine QA QC
• Rapid throughput with total run time of approximately 5.3 minutes per sample

Future Trends and Applications

Analysis may integrate backflush techniques for high throughput as per ASTM D7593. Advances may include automated sample handling alternative detectors and adaptation for diverse fuel types and engine fluids.

Conclusion

The established GC FID method provides accurate and repeatable quantification of gasoline dilution in engine oil in line with ASTM D3525 and JPI 5S 24 standards without the need for solvent pretreatment. It is suitable for high volume industrial testing environments.

Reference

• ASTM D3525-04 Standard Test Method for VOC Contamination in Crankcase Oil
• JPI 5S 24-2017 Japan Petroleum Institute Standard for Gasoline Dilution
• Shimadzu Application News No G312 for gasoline dilution analysis
• Shimadzu Application News No G313 for ASTM D7593 high throughput analysis