Kopi Talk
How to Choose Hydraulic Oil: An Easy 5-Point Buyer Check (Video Guide)
HKCT Lubricant Knowledge Series · Hydraulic Oil
“I need hydraulic oil… but which one should I choose?” It is one of the most common questions we hear from purchasers. The good news: learning how to choose hydraulic oil doesn’t have to be complicated. There are just a few things to check — and none of them start with the oil brand.
Watch the 2-minute buyer guide on how to choose hydraulic oil below, then use the 5-point checklist at the end of this article before your next purchase.
1. Start with your equipment — not the oil brand
Your equipment manual (or the machine builder) tells you what the hydraulic system needs. Before comparing any products, note down:
- Viscosity grade — e.g. ISO VG 32, 46 or 68
- Fluid type — e.g. HM (anti-wear) or HV (high viscosity index)
- Specifications the oil must meet
- OEM approvals, if the equipment maker requires any
What ISO VG 32, 46 and 68 actually mean
ISO VG 32, 46 and 68 are viscosity grades, measured at 40 °C. A higher number is not a better oil — it is simply a different (thicker) grade. The right grade is the one your equipment specifies.
And viscosity is only the start.
Same ISO VG does not mean the same product
Two oils can both be ISO VG 46 and still be different products. For example, an HM oil and an HV oil can share the same viscosity grade, but HV oil is formulated for a wider operating temperature range. That is why you should never compare hydraulic oils by viscosity alone.
2. Look at your actual operating conditions
Next, look at how the equipment really works day to day:
- Indoor or outdoor?
- Stable or changing temperatures?
- Normal or heavy load?
These answers help confirm whether the specified grade and fluid type suit your site, or whether the question should be raised with the equipment supplier or a lubricant specialist.
“I’m using another brand now. Can I change?”
Possibly. But first, compare the Product Data Sheets (PDS) against what your machine requires. Check the requirements — not just the product name.
3. Check compatibility before changeover
When you do change, ask one more question: are the old and new oils compatible, or should the system be drained and flushed first?
When to check with an expert
If your equipment needs a specific OEM approval, uses a special fluid, or you are not sure what oil is in the system now — don’t guess. Verify before switching.
How to choose hydraulic oil: the 5-point check
Before you buy hydraulic oil, confirm these five points:
- Correct ISO viscosity grade
正确 ISO 粘度等级 - Correct hydraulic-fluid type
正确液压油类型 - Specifications & OEM approvals
规格与 OEM 认证 - Actual operating conditions
实际工作条件 - Compatibility & changeover
相容性与换油方式
The right hydraulic oil isn’t chosen by one number.
Know the Requirement. Compare with Confidence.
选对液压油，不能只看一个数字。了解要求 · 放心比较
Watch in your preferred format
Bahasa Malaysia version — English voice-over with English & Bahasa Malaysia subtitles:
Ringkasan (Bahasa Malaysia)
Memilih minyak hidraulik tidak perlu rumit. Mulakan dengan keperluan peralatan anda, bukan jenama minyak. ISO VG 32, 46 dan 68 ialah gred kelikatan pada 40 °C — nombor lebih tinggi bukan bermakna lebih baik. Dua minyak dengan gred yang sama (contohnya HM dan HV) masih boleh berbeza. Semak keadaan operasi sebenar, bandingkan Lembaran Data Produk (PDS) dengan keperluan mesin, dan pastikan keserasian minyak lama dan baharu sebelum menukar — atau sama ada sistem perlu dikosongkan dan dibilas terlebih dahulu.
中文摘要
选择液压油，其实并不复杂。第一步从设备开始，而不是从品牌开始：设备手册会注明粘度、液压油类型、规格与 OEM 认证。ISO VG 32、46、68 是以 40 °C 测定的粘度等级，数字越高不代表越好。同为 ISO VG 46 的 HM 与 HV 油仍是不同的产品，HV 适用于更宽的温度范围。接着看设备的实际工作条件；如要更换品牌，先对照设备要求比较 PDS，并确认新旧油是否相容，或是否应先排空并冲洗系统。不确定时，别猜——更换前先确认。
Frequently asked questions
Is ISO VG 68 better than ISO VG 46?
No. ISO VG is a viscosity grade measured at 40 °C, not a quality rating. Use the grade your equipment manufacturer specifies.
Are two ISO VG 46 hydraulic oils interchangeable?
Not automatically. They may differ in fluid type (e.g. HM vs HV), specifications and OEM approvals. Compare the Product Data Sheets against your machine’s requirements.
Can I switch hydraulic oil brands?
Often yes, if the new oil meets all of the equipment’s requirements. Check compatibility with the oil currently in the system and whether a drain and flush is needed. If OEM approval is required or you’re unsure what’s in the system, verify first.
Need help checking a requirement? Still unsure how to choose hydraulic oil for your machine? Share your equipment model or the oil you are using now, and the HKCT team can help you compare Product Data Sheets against your machine’s requirements. Contact HKCT.
This article is general guidance. Always follow your equipment manufacturer’s recommendations.