If you’re a facility manager, construction foreman, or someone who rents or owns diesel-powered scissor lifts, you already know these workhorses don’t come cheap. They’re the backbone of jobs that require reaching 20, 30, even 50 feet high, and a small oversight can turn a full day of productive work into a broken machine stuck in a warehouse. As a diesel scissor lift supplier, I’ve spent the last 12 years walking side by side with operators and maintenance teams, and the number one mistake I see is skipping regular oil level checks—especially on the hydraulic and engine oils that keep these lifts moving. Diesel Scissor Lift
I get it. Between pre-trip inspections, loading and unloading, and meeting tight deadlines, routine checks can feel like a chore. But here’s the hard truth: a diesel scissor lift that runs low on oil is a disaster waiting to happen. The engine can seize up mid-lift, the hydraulic system can overheat, and suddenly you’re looking at thousands of dollars in repair bills, not to mention lost time on a critical job. Over the years, I’ve turned this specific task into a quick, no-fuss step that takes less than five minutes if you do it right, and I want to share that with you today.
First, let’s clarify a critical point: diesel scissor lifts have two separate oil systems, and mixing them up is a surefire way to damage your machine. There’s the engine oil, which lubricates the diesel power unit that drives the lift’s hydraulics and mobility, and then there’s hydraulic oil, which is the fluid that actually makes the scissor arms extend and retract. Most new operators (and even some veteran ones) grab the wrong dipstick during their first check, so I’m going to break both processes down clearly, step by step, so you never make that mistake.
Before you even touch the machine, there are a few non-negotiable prep steps to keep you safe and the lift in good shape. First, always park the scissor lift on a flat, solid, level surface. I can’t stress this enough—if the lift is tilted, your oil level reading will be wrong, and you’ll either add too much oil (which causes foaming and pressure issues) or not enough. Next, lower the scissor arms fully to their resting position, turn off the diesel engine, and set the emergency brake. If you’re working on a job site, chock the wheels to prevent any accidental movement while you’re under the platform. Last, wait at least 10 minutes after shutting off the engine. The oil needs time to drain back into its reservoirs; if you check right after turning off, it’s still circulating through the system, and your reading will be inaccurate.
Let’s start with the engine oil check, since that’s the first line of defense for your diesel power unit. Once you’ve completed your prep steps, pop the hood or access panel for the engine compartment—this is usually located at the rear of the scissor lift, near the wheel assembly, and marked with a bright “ENGINE OIL” sticker to avoid confusion. Look for the dipstick, which is usually a yellow or brass-colored handle, distinct from the red or blue hydraulic dipstick. Pull the dipstick out, wipe it clean with a lint-free rag or a paper towel, then push it all the way back in until it seats (not just resting on the threads—you need a full seal for an accurate reading). Pull it out again and check the oil level against the notches or hash marks on the dipstick. Most diesel scissor lift engines have two marks: “MIN” and “MAX.” The oil should sit exactly between these two lines, not touching the bottom of the MIN mark and not above the MAX mark. If it’s below MIN, you need to add the correct type of engine oil right away—always check your machine’s manual for the specific viscosity (usually 15W-40 for most models, but don’t guess). Never overfill, and if you’re topping up, add small amounts (about half a quart at a time), wait a minute, then recheck the level to avoid adding too much.
Now for the hydraulic oil check, which is the one that prevents the scissor arms from failing mid-lift. This is the system that handles the actual lifting force, so it needs precise oil levels to maintain pressure and prevent overheating. The hydraulic oil reservoir is usually larger than the engine oil reservoir, often located near the engine compartment or under the control panel on the side of the lift. The dipstick here is almost always red or has a distinct “HYDRAULIC OIL” label—take a second to confirm before you pull it out, because this is where mistakes happen. The prep steps here are slightly different: since the hydraulic system is under pressure, you need to make sure the lift is fully lowered and the engine is off, just like before, but don’t pull the dipstick when the engine is hot? Wait, no—actually, for hydraulic oil, some manufacturers recommend checking when the oil is warm, because it expands slightly and gives a more accurate level, as long as you wait 10 minutes after shutting off so it’s not still running. Pull the hydraulic dipstick, wipe it clean, reinsert fully, then pull it out to check. Again, look for “MIN” and “MAX” marks. If your scissor lift has an external sight gauge (some newer models do, to skip pulling the dipstick), that’s even easier: the oil should sit between the two lines on the clear glass or plastic gauge, with no bubbles or discoloration. If you see milky, dark, or gritty oil, that’s a sign of contamination, and you need to change it immediately—contaminated hydraulic oil is the number one cause of pump and cylinder failure on diesel scissor lifts.
Wait a second, I know what some of you are thinking: “I don’t have time for two different checks. Can’t I just check one?” No, you really can’t. The engine is the heart of your lift, and the hydraulics are the muscles—if either isn’t working right, the whole machine is useless. Over the years, I’ve had customers come to me with a lift that seized mid-job, and when we checked, they’d skipped the engine oil check because they only knew how to check the hydraulic oil. Or worse, they added hydraulic oil to the engine, costing them $8,000 in engine replacement because the wrong fluid caused all the moving parts to stop. Taking that extra 30 seconds to confirm which dipstick is which saves you months of headaches and thousands of dollars.
I also want to cover a few common pitfalls I see operators run into all the time. First, using the wrong oil type. Using standard motor oil instead of the specific diesel engine oil for your model can cause corrosion, reduced lubrication, and lower fuel efficiency. For hydraulic systems, using the wrong viscosity can lead to slow lift times in cold weather or overheating in hot temperatures—your machine’s manual will list the exact specs, so keep a copy in your lift’s cab or save it to your phone for quick reference. Second, ignoring oil quality, not just level. Even if your level is between MIN and MAX, if the oil is dark, smelly, or has metal shavings in it, that’s a sign that parts are wearing out and you need to address it before a breakdown. Third, checking the oil on a sloped surface. I once had a customer who checked his oil on a muddy job site where his lift was tilted, and he added two quarts of oil, only to find the level was way over MAX when he got to a flat area. That caused so much foaming that the engine lost pressure and threw a rod on a job for a local contractor, costing him a $15,000 repair and a lost contract with a large retail chain. Trust me, the 60 seconds it takes to find a flat spot is worth it.
Now, let’s talk about how often you should do these checks. For a lift that’s used every day on a construction site or busy facility, check the engine and hydraulic oil every morning before starting work as part of your pre-trip inspection. For lifts that are used occasionally, like those rented out for seasonal work, check the oil level before you put the lift into service and before you store it for long periods. If you notice any leaks around the engine or hydraulic hoses, check the oil level right away—leaks are a common cause of low oil, and addressing them early prevents more serious damage.
As a diesel scissor lift supplier, I’ve also noticed that many small business owners and independent operators cut corners on maintenance to save money, but that’s a false economy. A $20 quart of engine oil is way cheaper than a $5,000 engine repair, and a $50 hydraulic oil top-up is nothing compared to a week of downtime on a $100,000 job. I always tell my customers: if you take care of your lift, it’ll take care of you. Those 5-minute oil checks are the most cost-effective maintenance task you can do.
If you’re still not sure how to access the oil reservoirs on your specific model, or if you’ve never done a check before, don’t hesitate to reach out. We’re not just a supplier—we’re a team of mechanics and lift specialists who’ve been in the industry for decades, and we’re happy to walk you through the process over the phone or help you find a certified technician if you need hands-on support. For anyone looking to invest in a reliable diesel scissor lift, we offer a range of models built for every job, from compact 20-foot lifts for indoor work to heavy-duty 50-foot lifts for construction sites, all with clear maintenance guides and support to keep your machine running smoothly.
Regular oil level checks are non-negotiable for keeping your diesel scissor lift operational, safe, and cost-effective. Whether you’re a seasoned operator or new to working with aerial lifts, taking the time to do these simple checks every time you use your machine will save you from costly repairs, downtime, and safety risks. If you’re ready to invest in a reliable diesel scissor lift for your next project, or if you have questions about maintenance, don’t hesitate to connect with our team to discuss your needs.
Electric Suction Cup References
- Heavy Equipment Manufacturers Association. (2021). Preventive Maintenance Guidelines for Aerial Work Platforms.
- Caterpillar Inc. (2022). Diesel Engine Lubrication Best Practices for Construction Equipment.
- International Organization for Standardization. (2019). ISO 18878: Mobile elevating work platforms – Selection, dimensions, terminology and definitions.
- JLG Industries. (2023). Operator’s Manual for Diesel-Powered Scissor Lifts: Maintenance and Inspection Procedures.
Shandong Faster Machinery Co., Ltd.
Shandong Faster Machinery Co., Ltd. is one of the most reliable diesel scissor lift manufacturers and suppliers in China. With a professional production team, we are able to meet the needs of the majority of our customers. Please rest assured to buy advanced diesel scissor lift made in China here from our factory.
Address: No.76-4, Hainan Island Road, Qingdao, China.
E-mail: sales@fasterlift.com
WebSite: https://www.fasterlift.com/
