AUTOOL AS503Product OverviewThe AUTOOL AS503 is a handheld engine oil tester for gasoline and diesel vehicles. It uses optical probe technology to check engine oil transmittance and oil temperature, helping users evaluate oil contamination, oil quality, and replacement timing during automotive inspection and maintenance. Engine Oil Transmittance Gasoline / Diesel Modes Oil Temperature Display 10s Response2.8-inchBacklit LCD800mmPTFE Probe Hose6V4 × 1.5V Batteries3 YearsWarranty Support Click to enlarge Click to enlargeBefore You Order And UseBefore You Order And UseAS503 is designed for engine lubricating oil quality checks based on light transmission. Review the oil type limitation, engine limitation, test interval, and probe handling notes before ordering or using the tester.Engine Oil OnlyAS503 is intended for gasoline and diesel engine lubricating oil. It is not a brake fluid, transmission fluid, or power steering fluid tester.Optical Detection LimitBecause AS503 uses an optical detection probe, it is not suitable for engine oils containing molybdenum disulfide (MoS₂), organic molybdenum, graphene, or similar additives.Suzuki J20A Not SupportedAS503 does not support Suzuki J20A engine testing for the time being. Contact support before ordering if you need confirmation for this engine.Recommended Check IntervalUse AS503 as a reference check every 5,000-10,000 km, depending on engine condition, oil type, driving environment, and maintenance schedule.Probe Handling ReminderDo not force the hose or probe out if it becomes jammed.Wipe the probe clean before and after testing to reduce residue interference.Use the result as a maintenance reference together with actual oil condition and vehicle service requirements. Click to enlargeKey FeaturesKey FeaturesAS503 combines optical oil transmittance detection, oil temperature measurement, gasoline and diesel mode selection, a flexible PTFE probe hose, a backlit LCD, sound reminders, and a handheld body for quick engine oil checks.High-Precision Optical ProbeThe integrated photoelectric transceiver sensor detects engine oil transmittance to help evaluate oil contamination and impurity level.800mm Flexible PTFE HoseThe 800mm hose probe makes sampling easier around the engine bay. PTFE material resists oil, oxidation, and corrosion for longer service life.Gasoline And Diesel ModesSeparate gasoline and diesel engine oil modes help users check different lubricant oil standards more accurately.Oil Temperature MeasurementThe built-in temperature sensor displays the actual oil temperature and supports °C / °F switching for easier reading.2.8-Inch Backlit LCDThe backlit 2.8-inch screen shows battery level, selected engine type, transmittance, oil temperature, and result symbols clearly.Sound Alarm And Result ReminderThe tester uses screen icons and sound reminders to help users decide whether the oil is acceptable, needs attention, or should be replaced. Click to enlarge Click to enlarge Click to enlarge Click to enlarge Click to enlarge Click to enlarge Click to enlarge Click to enlargeMeasurement And Reading GuideMeasurement And Reading GuideEngine oil supports lubrication, cooling, rust prevention, cleaning, sealing, and buffering. AS503 gives a fast reference reading by checking oil transmittance and oil temperature, helping users decide when oil maintenance may be needed.Optical Probe ReadingThe probe reads light transmission through engine oil and reflects contamination or suspended particles that affect transparency.100%-50%When transmittance is between 100% and 50%, the tester generally indicates that oil replacement is not required yet.50%-30%When transmittance falls between 50% and 30%, the display shows a warning symbol to remind users to consider oil replacement.Below 30%When transmittance drops below 30%, the tester beeps and suggests replacing the engine oil as soon as possible for safety.Reading NoteThe AS503 result is a maintenance reference and should be considered together with mileage, oil type, engine condition, and service requirements.Oil temperature is shown with the T indicator and can be switched between °C and °F.AUTOOL AS503 has CE, FCC, and RoHS certifications and is designed for automotive aftermarket inspection and maintenance use.How To UseHow To UseUse the AS503 probe directly with engine oil, select the correct gasoline or diesel mode, and read the transmittance and oil temperature result after the test starts.Wipe The ProbeWipe the test probe clean before use to reduce residue interference.Remove The DipstickRemove the engine oil dipstick or access the engine oil testing point according to vehicle service requirements.Select Engine TypePress the engine type selection button to choose gasoline or diesel engine oil mode.Submerge The ProbePlace the testing probe into the engine oil and make sure the sensing area is properly submerged.Start The TestPress the test button and allow the tester to complete the reading process.Read The ResultThe display shows the transmittance percentage, result symbol, and current oil temperature. Click to enlargeUse NotesSelect the correct gasoline or diesel mode before testing.Do not force the hose or probe if it is stuck during removal.Clean the probe after testing to protect measurement accuracy and product life.SpecificationsAUTOOL AS503 Product SpecificationsAS503 is a 6V handheld engine oil quality tester with optical probe technology, 80cm PTFE test cable, 2.8-inch LCD screen, gasoline and diesel mode selection, and 10-second response time.DetectionProductAUTOOL AS503 Engine Oil Quality TesterDetection TechnologyOptical probe technologyOperating PrincipleEngine oil transmittanceSupported Oil TypeGasoline and diesel engine lubricating oilTest Mode SelectionGasoline engine / diesel engineTest Duration10s responseDisplay And ReadingDisplay2.8-inch backlit LCDReadingEngine oil transmittance percentage, oil temperature, result symbols, battery level, backlight, and sound indicatorTemperature Unit°C / °F switchableOil Temperature Measurement Range0-85°C / 0-185°FProbe And BodyTest Cable Length80cmHose MaterialPTFE / TeflonBody DesignHandheld body with silicone grip area for single-hand operationDimensions175 × 72 × 29mmPower And EnvironmentOperating Voltage6V, 4 × 1.5V batteriesOperating Temperature-10°C-60°CCertificationsCE, FCC, RoHSWarranty3-year warranty support for eligible non-human damage cases Click to enlarge DetectionProductAUTOOL AS503 Engine Oil Quality TesterDetection TechnologyOptical probe technologyOperating PrincipleEngine oil transmittanceSupported Oil TypeGasoline and diesel engine lubricating oilTest Mode SelectionGasoline engine / diesel engineTest Duration10s response Display And ReadingDisplay2.8-inch backlit LCDReadingEngine oil transmittance percentage, oil temperature, result symbols, battery level, backlight, and sound indicatorTemperature Unit°C / °F switchableOil Temperature Measurement Range0-85°C / 0-185°F Probe And BodyTest Cable Length80cmHose MaterialPTFE / TeflonBody DesignHandheld body with silicone grip area for single-hand operationDimensions175 × 72 × 29mm Power And EnvironmentOperating Voltage6V, 4 × 1.5V batteriesOperating Temperature-10°C-60°CCertificationsCE, FCC, RoHSWarranty3-year warranty support for eligible non-human damage cases Product ComparisonProduct ComparisonCompare AS503 with other AUTOOL oil and fluid analyzers before choosing the right tester for engine oil, brake fluid, transmission fluid, brake fluid boiling point, or power steering fluid.AS503 FocusEngine oil quality tester for gasoline and diesel engine oil transmittance with 2.8-inch LCD, 80cm PTFE cable, 6V power, °C / °F switching, and 10s response.Brake Fluid Water ContentAS501 and AS502 are brake fluid testers based on pressure boost detection technology for water content checks.Transmission FluidAS505 uses optical probe technology for automotive transmission fluid transmittance checks.Boiling Point TestingAS506 is a brake fluid boiling point tester using flash point heating technology and 12V power.Power Steering FluidAS507 is designed for automotive steering gear power steering fluid transmittance checks. Click to enlargeRelated ProductsRelated ProductsCompare related AUTOOL testers for brake fluid water content, engine oil quality, transmission fluid, brake fluid boiling point, and power steering fluid before choosing the right model. SALESelect options This product has multiple variants. The options may be chosen on the product page Add to wishlist Add to compare Quick view iconQuick view Oil Analysis TesterAUTOOL AS502 Car Brake Fluid Tester For Water Content TestingRated 0 out of 5(0) From US$30.00 Select options This product has multiple variants. The options may be chosen on the product page SALESelect options This product has multiple variants. The options may be chosen on the product page Add to wishlist Add to compare Quick view iconQuick view Oil Analysis TesterAUTOOL AS503 Engine Oil Tester with Digital DisplayRated 0 out of 5(0) From US$39.00 Select options This product has multiple variants. The options may be chosen on the product page Select options This product has multiple variants. The options may be chosen on the product page Add to wishlist Add to compare Quick view iconQuick view Oil Analysis TesterAUTOOL AS505 Exchanger Transmission Oil Tester with DisplayRated 0 out of 5(0) From US$49.00 Select options This product has multiple variants. The options may be chosen on the product page Select options This product has multiple variants. The options may be chosen on the product page Add to wishlist Add to compare Quick view iconQuick view Oil Analysis TesterAUTOOL AS506 Automobile Brake Fluid TesterRated 0 out of 5(0) From US$72.00 Select options This product has multiple variants. The options may be chosen on the product page Select options This product has multiple variants. The options may be chosen on the product page Add to wishlist Add to compare Quick view iconQuick view Oil Analysis TesterAUTOOL AS507 Power Steering Fluid Tester High Precision probeRated 0 out of 5(0) From US$30.00 Select options This product has multiple variants. The options may be chosen on the product page Manual And DownloadsManual And DownloadsDownload the AS503 user manual for operating steps, button functions, gasoline and diesel mode selection, oil transmittance reading, temperature display, and safe-use instructions. Click to enlargeAUTOOL AS503 User ManualOpen the PDF manual for AS503 setup, engine type selection, testing operation, display symbols, and maintenance guidance. Download ManualNeed Compatibility Confirmation?Contact AUTOOL Store before ordering if you need to confirm oil compatibility, Suzuki J20A limitation, MoS₂ / graphene oil limitation, battery setup, or AS series model selection. Email[email protected] WhatsApp 86 189 2647 7404 Click to enlargeWhat Is In The BoxWhat Is In The BoxThe package image shows the AS503 main unit, retail box, and user manual. Batteries are required for operation, but do not assume batteries are included unless confirmed by the final package listing.Main UnitAUTOOL AS503 engine oil quality tester with integrated flexible probeProbeBuilt-in 800mm PTFE / Teflon hose probeDocumentationUser manual shown in the package imagePackageAS503 retail box shown in the package imagePower RequirementRequires 4 × 1.5V batteries; inclusion should follow the final package listingQuestions And AnswersThese answers cover AS503 test function, gasoline and diesel modes, transmittance result reading, unsuitable oil additives, Suzuki J20A limitation, test interval, power supply, probe handling, package contents, and warranty support. What Does The AUTOOL AS503 Test? AS503 tests gasoline and diesel engine lubricating oil by checking oil transmittance with an optical probe. It also displays the current oil temperature to help users evaluate engine oil condition during maintenance. Can AS503 Test Both Gasoline And Diesel Engine Oil? Yes. AS503 supports separate gasoline engine and diesel engine oil mode selection. Select the correct engine type before starting the test. How Should I Read The Transmittance Result? When transmittance is between 100% and 50%, oil replacement is generally not required. When it is between 50% and 30%, the screen shows a warning symbol. When it drops below 30%, the tester beeps and suggests immediate oil replacement. Use the result together with actual vehicle service requirements. Which Engine Oils Are Not Suitable For AS503? AS503 relies on optical detection, so it is not suitable for engine oils containing molybdenum disulfide (MoS₂), organic molybdenum, graphene, or similar substances. These additives may affect optical analysis results. Does AS503 Support Suzuki J20A Engine Testing? No. AS503 does not support Suzuki J20A engine testing for the time being. Please contact AUTOOL Store before ordering if you need model or engine compatibility confirmation. How Often Should I Test Engine Oil? A practical reference is to check engine oil every 5,000-10,000 km, depending on oil type, driving conditions, vehicle age, engine condition, and the maintenance schedule recommended for the vehicle. What Batteries Does AS503 Use? AS503 uses 6V power from 4 × 1.5V batteries. Battery inclusion should follow the final package listing, so do not assume batteries are included unless confirmed. What Should I Do If The Hose Or Probe Gets Stuck? Do not force the hose or probe out if it becomes jammed. Stop operation, check the surrounding position carefully, and contact support if you are unsure how to remove it safely. What Is Included In The Box? Refer to the Packing List image for the final package contents. The image shows the AS503 main unit with integrated flexible probe, user manual, and retail box. AS503 requires 4 × 1.5V batteries; battery inclusion should follow the final package listing. What Is The Difference Between AS503 And Other AUTOOL Fluid Testers? AS503 is for gasoline and diesel engine oil transmittance testing. AS501 and AS502 are brake fluid water content testers. AS505 is for transmission fluid transmittance. AS506 is a brake fluid boiling point tester. AS507 is for power steering fluid transmittance. How Long Is The Warranty? AUTOOL provides 3-year warranty support for eligible non-human damage cases. For damage caused by non-human factors, AUTOOL may provide replacement parts within the warranty policy. Contact support for setup, compatibility, package, or troubleshooting help. Can AS503 Replace Professional Oil Laboratory Analysis? No. AS503 is a practical automotive maintenance reference tool for quick oil transmittance and temperature checks. For detailed chemical composition, wear metal analysis, or laboratory-grade diagnosis, use professional oil analysis services.Warranty And ContactWarranty And ContactFor AS503 oil compatibility, Suzuki J20A limitation, MoS₂ / graphene additive limitation, battery setup, result interpretation, probe handling, package confirmation, warranty, or AS series model selection, contact AUTOOL Store directly.Pre-Sales And Product SupportUse support if you need help confirming whether AS503 is suitable for your engine oil, vehicle, or maintenance scenario. AUTOOL support can also help with AS502 / AS503 / AS505 / AS506 / AS507 model selection and package confirmation.3-year warranty support for eligible non-human damage casesOil compatibility and additive limitation confirmationSuzuki J20A engine limitation confirmationBattery setup and display symbol explanationProbe handling and stuck hose guidancePackage contents and AS series model comparison supportCustomer support response as soon as possible, generally within 24 hours Email Support[email protected] WhatsApp Support 86 189 2647 7404