AUTOOL AS503 Engine Oil Tester for Petrol & Diesel Engines

AUTOOL AS503 Engine Oil Quality Tester

Optical Oil Condition Tester for Petrol & Diesel Engines

The AUTOOL AS503 checks engine oil condition by measuring how much light passes through the oil. Transmittance drops as soot, sludge and suspended particles build up, so the result tells you in seconds whether the oil can stay in, needs watching or should be changed.

Select petrol or diesel mode, insert the flexible probe through the dipstick tube and read the transmittance and oil temperature on the 2.8-inch backlit screen. It's a quick check between services, or before buying a used car.

AUTOOL AS503 engine oil quality tester for petrol and diesel engines

Main Features

Oil transmittance reading: measures how clean the oil is, shown as a percentage.
Clear result: 100–50% no change needed, 50–30% warning, below 30% beeps and suggests an immediate change.
Petrol and diesel modes: separate settings for each engine type.
Oil temperature: built-in sensor reads 0–85 °C, in °C or °F.
Flexible 800 mm PTFE probe: oil- and corrosion-resistant, fits down the dipstick tube.
2.8-inch backlit screen: shows transmittance, temperature, engine type and result symbols.
Compact handheld design: easy to carry for mobile servicing.

Important Notes

A screening tool, not a laboratory oil analysis. It does not measure viscosity, wear metals or remaining oil life.
Not suitable for oils containing molybdenum disulfide (MoS₂), organic molybdenum or graphene additives, which affect optical readings.
Does not support the Suzuki J20A engine.
For engine oil only. Suggested check interval: every 5,000–10,000 km.
Runs on 4 × AAA batteries.

Package Includes

1 × AUTOOL AS503 engine oil tester with PTFE probe
1 × User manual

Why Mechanics Choose the AS503

Transmittance %	An objective reading instead of judging oil by colour
Keep / warning / change result	Clear advice to share with customers
Petrol and diesel modes	One tester for the whole fleet
Oil temperature reading	Context for every result
Dipstick-tube probe	No need to drain a sample
Results in seconds	Fits into any service or inspection

AUTOOL AS503 engine oil tester with flexible PTFE probe

AUTOOL AS503 Technical Specifications

Application	Engine oil condition screening
Test Method	Optical transmittance
Engine Modes	Petrol, diesel
Results	Transmittance %, keep / warning / change
Oil Temperature	0–85 °C (°C / °F)
Display	2.8-inch backlit LCD
Probe	800 mm flexible PTFE hose
Power	4 × AAA 1.5 V batteries (6 V)
Dimensions	175 × 72 × 29 mm
Warranty	3 years main unit, 1 year accessories (manufacturer)

AUTOOL AS503 oil condition tester with 2.8-inch screen

Delivery

99% of purchases are dispatched from our Melbourne warehouse within 24 hours of payment. Every parcel is shipped with Australia Post e-Parcel, complete with tracking and signature on delivery.

Need it sooner? Express shipping is also available—check if your postcode is in the Next Day Delivery network.

Returns

Shop with confidence. We offer a 30-day money back guarantee on all orders. If you’ve had a change of mind, simply return the item in re-original condition and we’ll make it right.

Warranty

All AZscanners products are backed by a 12-month warranty (unless otherwise stated). We stand by the quality of our tools and will repair or replace your item if a covered fault arises.

Buying your scan tool should feel easy, safe, and backed by a team you can trust.

That’s why thousands of mechanics, fleets, and car owners across Australia choose AZscanners. Here’s our promise to you:

Trusted Since 2013

We’ve been Australia’s go-to supplier of premium diagnostic scan tools for over a decade. From workshops and mobile mechanics to DIY users, we’ve built our reputation on quality, reliability, and real support.

30-Day Money Back Guarantee

Changed your mind? No problem. You have 30 days to return your item in its original condition for a full refund. It’s our way of making your purchase completely risk-free.

Quality You Can Count On

Every product in our range is hand-picked for performance, compatibility, and durability. Whether you’re after a professional-grade scan tool or an easy solution for home use, we’ve got you covered.

Local Support that Cares

We don’t just sell scan tools — we support them. Our team of technicians is here to answer your questions before and after purchase, so you’re never left on your own.

Fast & Reliable Shipping

99% of orders are shipped within 24 hours (from our Melbourne warehouse) with tracking and signature included. Need it quicker? Express delivery is available.