AUTOOL AS503 Engine Oil Tester with Digital Display

(22 customer reviews)

Price range: US$38.90 through US$138.00

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AUTOOL AS503

Product Overview

The 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 Response
2.8-inchBacklit LCD
800mmPTFE Probe Hose
6V4 × 1.5V Batteries
3 YearsWarranty Support
AUTOOL AS503 engine oil quality tester main product image with key functions Click to enlarge
AUTOOL AS503 engine oil tester 3-year warranty image Click to enlarge
Before You Order And Use

Before You Order And Use

AS503 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 Only

AS503 is intended for gasoline and diesel engine lubricating oil. It is not a brake fluid, transmission fluid, or power steering fluid tester.

Optical Detection Limit

Because 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 Supported

AS503 does not support Suzuki J20A engine testing for the time being. Contact support before ordering if you need confirmation for this engine.

Recommended Check Interval

Use AS503 as a reference check every 5,000-10,000 km, depending on engine condition, oil type, driving environment, and maintenance schedule.

Probe Handling Reminder

  • Do 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.
AUTOOL AS503 caution image for oils containing molybdenum disulfide organic molybdenum or graphene Click to enlarge
Key Features

Key Features

AS503 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 Probe

The integrated photoelectric transceiver sensor detects engine oil transmittance to help evaluate oil contamination and impurity level.

800mm Flexible PTFE Hose

The 800mm hose probe makes sampling easier around the engine bay. PTFE material resists oil, oxidation, and corrosion for longer service life.

Gasoline And Diesel Modes

Separate gasoline and diesel engine oil modes help users check different lubricant oil standards more accurately.

Oil Temperature Measurement

The built-in temperature sensor displays the actual oil temperature and supports °C / °F switching for easier reading.

2.8-Inch Backlit LCD

The backlit 2.8-inch screen shows battery level, selected engine type, transmittance, oil temperature, and result symbols clearly.

Sound Alarm And Result Reminder

The tester uses screen icons and sound reminders to help users decide whether the oil is acceptable, needs attention, or should be replaced.

Measurement And Reading Guide

Measurement And Reading Guide

Engine 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 Reading

The 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 Note

  • The 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 Use

How To Use

Use 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 Probe

Wipe the test probe clean before use to reduce residue interference.

Remove The Dipstick

Remove the engine oil dipstick or access the engine oil testing point according to vehicle service requirements.

Select Engine Type

Press the engine type selection button to choose gasoline or diesel engine oil mode.

Submerge The Probe

Place the testing probe into the engine oil and make sure the sensing area is properly submerged.

Start The Test

Press the test button and allow the tester to complete the reading process.

Read The Result

The display shows the transmittance percentage, result symbol, and current oil temperature.

AUTOOL AS503 operating steps for wiping probe removing dipstick selecting engine type submerging probe starting test and reading results Click to enlarge

Use Notes

  • Select 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.
Specifications

AUTOOL AS503 Product Specifications

AS503 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.

Detection
ProductAUTOOL AS503 Engine Oil Quality Tester
Detection TechnologyOptical probe technology
Operating PrincipleEngine oil transmittance
Supported Oil TypeGasoline and diesel engine lubricating oil
Test Mode SelectionGasoline engine / diesel engine
Test Duration10s response
Display And Reading
Display2.8-inch backlit LCD
ReadingEngine oil transmittance percentage, oil temperature, result symbols, battery level, backlight, and sound indicator
Temperature Unit°C / °F switchable
Oil Temperature Measurement Range0-85°C / 0-185°F
Probe And Body
Test Cable Length80cm
Hose MaterialPTFE / Teflon
Body DesignHandheld body with silicone grip area for single-hand operation
Dimensions175 × 72 × 29mm
Power And Environment
Operating Voltage6V, 4 × 1.5V batteries
Operating Temperature-10°C-60°C
CertificationsCE, FCC, RoHS
Warranty3-year warranty support for eligible non-human damage cases
AUTOOL AS503 specifications including operating voltage operating temperature dimensions and button functions Click to enlarge
Detection
ProductAUTOOL AS503 Engine Oil Quality Tester
Detection TechnologyOptical probe technology
Operating PrincipleEngine oil transmittance
Supported Oil TypeGasoline and diesel engine lubricating oil
Test Mode SelectionGasoline engine / diesel engine
Test Duration10s response
Display And Reading
Display2.8-inch backlit LCD
ReadingEngine oil transmittance percentage, oil temperature, result symbols, battery level, backlight, and sound indicator
Temperature Unit°C / °F switchable
Oil Temperature Measurement Range0-85°C / 0-185°F
Probe And Body
Test Cable Length80cm
Hose MaterialPTFE / Teflon
Body DesignHandheld body with silicone grip area for single-hand operation
Dimensions175 × 72 × 29mm
Power And Environment
Operating Voltage6V, 4 × 1.5V batteries
Operating Temperature-10°C-60°C
CertificationsCE, FCC, RoHS
Warranty3-year warranty support for eligible non-human damage cases
Product Comparison

Product Comparison

Compare 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.
AUTOOL AS501 AS502 AS503 AS505 AS506 AS507 automotive oil and fluid analyzer comparison chart Click to enlarge
Related Products

Related Products

Compare 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.

Manual And Downloads

Manual And Downloads

Download the AS503 user manual for operating steps, button functions, gasoline and diesel mode selection, oil transmittance reading, temperature display, and safe-use instructions.

AUTOOL AS503 engine oil quality tester user manual preview Click to enlarge

AUTOOL AS503 User Manual

Open the PDF manual for AS503 setup, engine type selection, testing operation, display symbols, and maintenance guidance.

Download Manual

Need 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.

AUTOOL AS503 packing list showing main unit retail box and user manual Click to enlarge
What Is In The Box

What Is In The Box

The 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 probe
ProbeBuilt-in 800mm PTFE / Teflon hose probe
DocumentationUser manual shown in the package image
PackageAS503 retail box shown in the package image
Power RequirementRequires 4 × 1.5V batteries; inclusion should follow the final package listing

Questions And Answers

These 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.

Warranty And Contact

Warranty And Contact

For 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 Support

Use 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 cases
  • Oil compatibility and additive limitation confirmation
  • Suzuki J20A engine limitation confirmation
  • Battery setup and display symbol explanation
  • Probe handling and stuck hose guidance
  • Package contents and AS series model comparison support
  • Customer support response as soon as possible, generally within 24 hours

Customer Reviews

  1. 5
    (22 customer reviews)
    100% of customers recommend this product.
    5 Stars100%4 Stars0%3 Stars0%2 Stars0%1 Star0%
  2. Heiszler

    I just got my package! I will test it and come back with feedback

    0 of 0 found this review helpful
  3. S¨¦rgio Brand?o (verified owner)

    Very quickly, good material.

    0 of 0 found this review helpful
  4. Brian Cook (verified owner)

    I really appreciate being able to use this engine oil tester. The technology is amazing to me. There are a few changes I would make to the device. The probe should be slightly longer. I had to push the probe in all the way to the handheld unit to get an accurate test result. The metal tip of the probe could be improved. The sharp metal edges need to be smooth so that they don’t cause the probe to become stuck. It wasn’t easy for me to remove the probe every time.

    0 of 0 found this review helpful
  5. Dariusz Kr¨®l (verified owner)

    Kolejne przydatne urz?dzenie tej firmy jest bardzo pomocne w moim domowym warsztacie przy obs?udze samochodu. Polecam

    0 of 0 found this review helpful
  6. Adam Piatczak (verified owner)

    Very good product. High recommended !

    0 of 0 found this review helpful
  7. Osborn Bentham

    This engine oil tester can clearly detect the transmittance of the oil, the display is clear and crisp, very good to use£¡Trust AUTOOL’s quality!

    0 of 0 found this review helpful
  8. Bruce T Elwell

    Bought this to check my oils condition on my car also for my oil cooler. If the oil temperature ever rises too high I know this will need to be changed

    0 of 0 found this review helpful
  9. Bernard Pathirana (verified owner)

    AUTOOL AS503 Engine Oil Tester with Digital Display for Auto Check Gasoline & Diesel Car Engine POA Oil Quality Repair Tools

    0 of 0 found this review helpful
  10. Serban Bogdan (verified owner)

    Nice product, I can say in new oil 100% corect, in used one 9000km on disel car used oil 30% remaining but it’s not seeing the oil it’s polluted with diesel , and probably the friction it’s more bad for the engine .

    0 of 0 found this review helpful
  11. Ethel Horace

    The tool is very useful, the check is very accurate, helped me to solve many ware quality problems, effectively improve the power of the car!

    0 of 0 found this review helpful
  12. Makis (verified owner)

    Exactly how it was described..,excellent service!!!
    I will buy again

    0 of 0 found this review helpful
  13. herry

    I’m really impressed with this tester because it enables me to test multiple specific types of DOT brake fluid. Compared to those small pencil – type brake fluid testers, this meter is significantly more accurate.

    0 of 0 found this review helpful
  14. Cash Yonng

    Exceeded my expectations! The operation is very simple, just insert the probe into the oil and it shows the health of the oil in a few seconds, making it easy for me to determine if I need to change the oil.

    The measurement results are very intuitive, the green light means the oil is in good condition, the yellow light reminds that attention is needed, and the red light indicates that it’s time to change the oil, which is very practical! I used it to test several cars of my own and my friends’, and the results were very accurate, greatly reducing the cost of unnecessary oil changes.

    0 of 0 found this review helpful
  15. jrpete

    Try it if it’s accurate and. Good item.

    0 of 0 found this review helpful
  16. Richard

    Okay good. Hope it will last. Having the tool makes working more confident. Garage guys should buy and use it.

    0 of 0 found this review helpful
  17. Enrique Hernandez (verified owner)

    What I don’t like is that an oil with 6k miles and a fairly dark color says it has 100% life…

    0 of 0 found this review helpful
  18. Betty Chaucer

    The operation is simple, the detection is accurate, and the detection time is short. It can be measured in just a few seconds.

    0 of 0 found this review helpful
  19. ville chen

    Good product, shows that it is of very good quality compared to what it costs, works very well.

    0 of 0 found this review helpful
  20. Clement Nathaniei

    This AUTOOL AS503 engine oil tester is really useful! It only takes a few seconds to determine if the oil should be replaced, no more feeling or blindly changing the oil, saving money and the environment. It’s very easy to operate, plug in the power, plug in the probe, and the readings are clear at a glance, making it suitable for individual car owners as well as maintenance stores.

    0 of 0 found this review helpful
  21. Nikolai Marinov (verified owner)

    Super

    0 of 0 found this review helpful
  22. Oliver Woolf

    I compared it with other brands’ testers, and it delivers accurate results with fast detection speed. The product feels premium and is very easy to use.

    0 of 0 found this review helpful
  23. Thettalos (verified owner)

    I think it works for real!

    0 of 0 found this review helpful
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AUTOOL AS503 Engine Oil Tester with Digital Display
AUTOOL AS503 Engine Oil Tester with Digital Display

Price range: US$38.90 through US$138.00

Add to cart This product has multiple variants. The options may be chosen on the product page