---
product_id: 5420113
title: "OTC 5025 Diesel Exhaust Fluid (DEF) Refractometer"
brand: "otc"
price: "€ 236.96"
currency: EUR
in_stock: true
reviews_count: 8
category: "Otc"
url: https://www.desertcart.gr/products/5420113-otc-5025-diesel-exhaust-fluid-def-refractometer
store_origin: GR
region: Greece
---

# Quick, on-the-go DEF concentration check Precision optical measurement Complete kit with tools & case OTC 5025 Diesel Exhaust Fluid (DEF) Refractometer

**Brand:** otc
**Price:** € 236.96
**Availability:** ✅ In Stock

## Summary

> 🔍 Stay precise, stay compliant—never let your DEF concentration slip!

## Quick Answers

- **What is this?** OTC 5025 Diesel Exhaust Fluid (DEF) Refractometer by otc
- **How much does it cost?** € 236.96 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.gr](https://www.desertcart.gr/products/5420113-otc-5025-diesel-exhaust-fluid-def-refractometer)

## Best For

- otc enthusiasts

## Why This Product

- Trusted otc brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Regulation-Ready:** Ensures compliance with EPA NOx emission standards for all diesel engines post-2010—stay ahead of inspections.
- • **All-Inclusive Kit:** Comes with dropper, lens cloth, screwdriver, and protective case—everything you need for professional DEF testing.
- • **Portable Powerhouse:** Compact and lightweight design (just 1 gram!) lets you test DEF anytime, anywhere—no bulky gear needed.
- • **User-Friendly Scale:** Easy-to-read reticle calibrated for 15-40% concentration range, simplifying fluid quality checks in seconds.
- • **Pinpoint DEF Accuracy:** Measure Diesel Exhaust Fluid concentration with ±0.5% precision for flawless SCR performance.

## Overview

The OTC 5025 Diesel Exhaust Fluid Refractometer is a precision, portable optical tool designed to measure DEF concentration with ±0.5% accuracy. Essential for diesel engines using SCR technology to meet EPA NOx emission standards, it features an easy-to-read scale calibrated for the critical 32.5% urea solution. Lightweight and compact, it includes a complete kit for on-the-spot testing, ensuring your vehicle’s emission system runs flawlessly and stays inspection-ready.

## Description

The Refractometer is a portable, precision, optical instrument used for measuring the Diesel Exhaust Fluid (DEF) concentration. When a liquid sample is placed on the prism, the light passing through it is bent. The more concentrated the liquid, the more the light will bend. The Refractometer contains a reticle, or scale, that is enlarged through the eyepiece to measure this light. The values on the scale have been established to evaluate the DEF condition. EPA regulations require all diesel engines manufactured on or after January 1, 2010 to meet lowered NOx emissions standards. Most heavy duty engine (Class 7-8 trucks) manufacturers, have chosen to utilize SCR. This Includes Detroit Diesel (DD13, DD15, and DD16 models), Cummins (ISX line), PACCAR, and Volvo/Mack. SCR-equipped engines require the periodic addition of Diesel Exhaust Fluid (DEF, a urea solution) to enable the process. DEF is available in a bottle from most truck stops, and some have installed bulk DEF dispensers near the Diesel Fuel pumps. However, to ensure the proper operation of the SCR system, operators must ensure the DEF in their vehicle consists of a 32.5 percentage Urea/Water solution. It makes this a simple and quick process for an operator or technician. Scale: 0.5 percentage, line graduations 32.5 percentage, indicated scale 15-40 percentage, waterline, and 20 degree Celsius kit includes Refractometer, dropper, lens wipe cloth, instructions and quick guide, screwdriver and case.

Review: Works as advertized - Easy to use and read display. Accuracy unknown for lack of a known calibration fluid other than water, but new package of Blue DEF checked good.
Review: What a great tool to have at a good price - Just bought a new 2023 semi truck $220k didn’t even have 3k miles when a check engine light with poor def truck derated shop said def was contaminated. I got a bill of $1900. I sent bill to seller he paid the bill contamination is not cover under warranty somebody had to pay that bill truck got fixed bought this tool every jug I put in I test well 3k miles again check engine light poor def again I told shop I checked every jug bought def fluid from there parts counter well shop gave me a bill for $6,200 i checked fluid and showed my refractometerwell they started doing there job come to find out the builder of the truck for some reason caked on a bunch of grease on O-ring that goes on sensor that was leaking into the tank and creating false readings and that’s where the contamination was coming from. I suggest if you have a semi truck that uses DEF buy this tool it’s worth every penny. By the way, the $6200 bill got covered under warranty.

## Features

- The refractometer is a portable precision optical instrument used for measuring the diesel exhaust fluid concentration
- When a liquid sample is placed on the prism the light passing through it is bent and the more concentrated the liquid the more the light will bend
- The refractometer contains a reticle or scale that is enlarged through the eyepiece to measure this light and the values on the scale have been established to evaluate the DEF condition
- EPA regulations require all diesel engines manufactured on or after January 1 2010 to meet lowered NOx emissions standards
- Most heavy duty engine manufacturers have chosen to utilize SCR including Detroit Diesel DD13 DD15 DD16 Cummins ISX line PACCAR and Volvo-Mack

## Technical Specifications

| Specification | Value |
|---------------|-------|
| Brand | OTC |
| Item dimensions L x W x H | 12.3 x 5.9 x 2.85 inches |
| Item Weight | 1 Grams |
| UPC | 731413559846 |
| Global Trade Identification Number | 00731413559846 |
| Manufacturer | OTC |
| Model | 5025 |
| Item Weight | 0.035 ounces |
| Product Dimensions | 12.3 x 5.9 x 2.85 inches |
| Item model number | 5025 |
| Is Discontinued By Manufacturer | No |
| Manufacturer Part Number | 5025 |
| OEM Part Number | 5025 |

## Product Details

- **Brand:** OTC
- **Item dimensions L x W x H:** 12.3 x 5.9 x 2.85 inches
- **Item Weight:** 1 Grams
- **UPC:** 731413559846
- **Global Trade Identification Number:** 00731413559846

## Images

![OTC 5025 Diesel Exhaust Fluid (DEF) Refractometer - Image 1](https://m.media-amazon.com/images/I/81z5AAkks3L.jpg)

## Customer Reviews

### ⭐⭐⭐⭐⭐ Works as advertized
*by S***T on July 9, 2021*

Easy to use and read display. Accuracy unknown for lack of a known calibration fluid other than water, but new package of Blue DEF checked good.

### ⭐⭐⭐⭐⭐ What a great tool to have at a good price
*by E***S on February 25, 2023*

Just bought a new 2023 semi truck $220k didn’t even have 3k miles when a check engine light with poor def truck derated shop said def was contaminated. I got a bill of $1900. I sent bill to seller he paid the bill contamination is not cover under warranty somebody had to pay that bill truck got fixed bought this tool every jug I put in I test well 3k miles again check engine light poor def again I told shop I checked every jug bought def fluid from there parts counter well shop gave me a bill for $6,200 i checked fluid and showed my refractometerwell they started doing there job come to find out the builder of the truck for some reason caked on a bunch of grease on O-ring that goes on sensor that was leaking into the tank and creating false readings and that’s where the contamination was coming from. I suggest if you have a semi truck that uses DEF buy this tool it’s worth every penny. By the way, the $6200 bill got covered under warranty.

### ⭐⭐⭐⭐⭐ Functionality.
*by D***T on October 23, 2025*

So easy to use, the pamphlet instruction is included, it cost less than you order directly from OTC. The glass screen show your DEF testing fluids very clearly and 99% accuracy, works as it design for.

## Frequently Bought Together

- OTC 5025 Diesel Exhaust Fluid (DEF) Refractometer
- Performance Tool W16500 Professional DEF Tester (Disc Type DEF, Diesel Exhaust Fluid tester)
- EISCO Plastic Graduated Cylinder, 500mL - Class B - Stable Hexagonal Base - Premium Polypropylene - Lab Cylinder, Measuring Cylinder

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*Product available on Desertcart Greece*
*Store origin: GR*
*Last updated: 2026-02-21*