One-Tool OTO350 User Manual Download Page 2

oil quality reading. If test results show that oil quality does 

not drop as expected over time or seems to improve, check 

engine for fuel leaks. (Try a drop of oil on paper. Look for a 

gray ring.) If a significantly worse oil rating than expected is 

displayed, we recommend having the engine checked, or 

send a sample to an oil laboratory for analysis.

COMMON CAUSES OF INACCURATE READING 

1. The sensor and oil bowl are not clean.

2. The oil surface do not reach the required height as

indicated in Fig.3

3. The additives of the engine oil may result in inconsistent

testing results of one oil sample for each time testing, the

accuracy should be ± 5%.

4. The sensor is sensitive to working temperature and relative

humidity. Dampness or severe heat or cold environment

may affect testing result.

5.

If engine oil condition is inconsistent with testing result,

calibration is required.

CALIBRATION

Calibration has been done under GAS1 mode after they are 

out of factory. For engine oil dealer or manufacturer, we advise 

calibrating the instrument by themselves for each certain kind

of engine oil due to different additives, which may affect testing 

result significantly. Also,we advise calibrting the instrument 

when the working temperature and relative humidity changed

dramatically or the engine oil condition is inconsistent with 

testing result.

How to Calibrate?

1. When the instrument is OFF, press and hold the Back

button, and then press the Power button. The unit is ON.

2. Select the oil mode you need to set and then press the

Power or Next button. The unit is now under calibration

procedure.

3. Drop Calibration oil to the testing bowl, which must be old

oil close or recommend to change.

4. Press the Power button to execute calibrating until the

display shown done as in Fig.4 below. Wipe the oil bowl

with clean and dry paper towel.

5. As indicated on the display, drop new oil to be tested to the

testing bowl. Press the Power button to execute calibrating

until the display shown result stored as shown in Fig.5

below.

6. Press the Back button to the main menu and then press

the Power button to turn the unit OFF. Calibration is

complete.

7. Wipe the oil bowl with clean and dry paper towel.

Important:

The old and new oil for calibration must be the same

certain kind of engine oil.

The old oil for calibration must reach a maximum

acceptable level (oil close or recommend to change).

Fig.4

Fig.5

CHARGING THE INSTRUMENT

Please charge the instrument with power adaptor when the 

unit indicates low battery. The charging light will turn from red 

to green when the battery is full.

SPECIFICATIONS 

Application

˖

The instrument is designed to test gasoline or 

diesel engine oil. 

Display

˖

128*64 LED Display 

Power Supply 

˖

3.7V Li rechargeable battery with 1000

P

Ah

Operating Environment: Working Temperature 10

ć

-27 

ć

Relative Humidity < 80%

Accuracy

˖

± 5%

Dimensions

˖

145x85x20mm

MAINTENANCE

This instrument is designed for indoor use only. Do not

use the instrument in rain.

Keep the oil bowl and sensor dry and clean. After each

time testing, cleaning should be done to the oil bowl

and sensor with a clean and dry paper towel.

Keep the instrument in its carrying case when not in

use and do not subject it to dampness or severe heat

or cold.

WARRANTY

This instrument is warranted against defects of material or 

workmanship which develop within a period of six months 

following the date of purchase by the original owner.

The unit is a sealed instrument and contains no user 

serviceable parts. Opening other parts of the unit will void the 

warranty.

Drop Cal Oil // 
Done 
Drop new Oil 

Drop Cal Oil 
Done 
Drop new oil 
Result stored

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