Buy Mercedes-Benz SL500 Hydraulic System Fluids

On SL500 (R230 generation) cars, ABC suspension was widely fitted. That system uses central hydraulic fluid, not brake fluid or regular ATF. (Wikipedia)
On earlier SL500 (R129 generation) cars, the big hydraulic user is the convertible top (and related level/assist systems). Those hydraulics use a different spec fluid (see below). (Wikipedia)

• Most SL500 (R230) cars with ABC use hydraulic fluids that meet Mercedes-Benz sheet 345.0 (often called "CHF"). A well-known example is Pentosin CHF 11S, which is dark green and explicitly lists MB 345.0 among its approvals. CHF 202 is a newer fluid in the same family. Always follow the spec on your cap/manual. (Mercedes-Benz Operating Fluids)
• SL500 (R129) soft-top hydraulics typically use ZH-M mineral hydraulic oil that meets Mercedes-Benz sheet 343.0 (a different spec than 345.0). Mercedes' official "BeVo" page lists the approved 343.0 fluids and where they are used (level control, hydropneumatic suspension, soft top, etc.). (Mercedes-Benz Bevo, Benzbits)

Mercedes publishes official "BeVo" operating-fluid sheets that list the approved spec numbers and examples:

• MB 345.0 - Hydraulic fluids (for central hydraulic systems like ABC). See the current sheet here. (Mercedes-Benz Operating Fluids)
• MB 343.0 - ZH-M hydraulic oil (used on earlier systems such as soft tops). Approved products and the use cases are listed here. (Mercedes-Benz Bevo)

• Pentosin CHF 11S (central hydraulic fluid): lists MB 345.0 on its data sheet and shows Appearance: Dark Green plus typical viscosity data.
• CHF 202 (successor type): reputable manufacturer data notes CHF 11S and CHF 202 are compatible and used in the same kinds of systems; both are central hydraulic fluids (not brake fluid). (Fuchs, Petroleum Service Company)
• ZH-M (MB 343.0): manufacturer literature identifies this as the correct mineral hydraulic oil for systems calling for MB 343.0 (often dyed yellow/light beige in practice). (Mercedes-Benz Bevo, German Parts)

• OK to mix: CHF 11S ↔ CHF 202 (same family). Multiple data sheets from OEM lubricant makers say they are suitable for blending. (Fuchs, Petroleum Service Company)
• Do not mix: CHF 11S/202 with older CHF 7.1 or with ZH-M (MB 343.0) mineral oil; also never with DOT brake fluid or ATF. This isn't just preference-manufacturers warn CHF 11S/202 should not be blended with older formulas or "other hydraulic oils." Using the wrong chemistry can damage pumps, seals, and valves.

Always follow the owner's manual and the note on the reservoir cap. ABC systems often have a level mark on a dipstick in the tank; some checks are done at normal ride height and specific engine conditions. Use only the correct spec to top up. (Here's a direct link to an SL (R230) owner's manual as a reference.) (static.oneweb.mercedes-benz.com)

Mercedes doesn't publish a regular fluid/filter service interval for ABC (it's considered "maintenance-free"), but Mercedes' technical training article explains why proactive fluid & filter changes help: the fluid is hygroscopic, works under ~200 bar (≈2,900 psi), and a small filter in the reservoir can load up. Dirty or moisture-laden fluid accelerates wear and can lead to costly failures. Many techs treat periodic fluid/filter service as smart prevention.

If the wrong fluid is used, the level is low, or the fluid is dirty, you may notice warning messages, noise, foaming, a harsh ride, or even a suspension corner sinking after parking. The Mercedes StarTuned article walks through common issues (accumulator failures, pump priming needs, valve block debris) and stresses clean fluid and correct procedures.

Treat used hydraulic oil like used oil-keep it contained and recycle it properly. The U.S. EPA explains best practices for handling and recycling used oil and oil-soaked materials; similar rules exist in many regions worldwide. Don't pour it down a drain or onto the ground. (US EPA)

• ABC / central hydraulics (R230 SL500) → look for MB 345.0 on the cap/fluid; fluid is typically green (e.g., CHF 11S/202).
• Convertible-top hydraulics (R129 SL500) → look for MB 343.0; fluid is ZH-M (mineral). (Mercedes-Benz Bevo)

• Mercedes-Benz BeVo 345.0 (hydraulic fluids) - official spec list. (Mercedes-Benz Operating Fluids)
• Mercedes-Benz BeVo 343.0 (ZH-M fluids) - official spec list. (Mercedes-Benz Bevo)
• Pentosin CHF 11S data sheet - approvals, color, properties.
• FUCHS information on CHF 11S / CHF 202 compatibility. (Fuchs)
• Mercedes SL (R230) owner's manual - operating details. (static.oneweb.mercedes-benz.com)
• EPA: How to manage/recycle used oil. (US EPA)

Q: What hydraulic fluid does a 2003-2008 SL500 with ABC use?
A: Use a central hydraulic fluid that meets Mercedes sheet 345.0 (often called CHF). A common example is Pentosin CHF 11S. Check your cap/manual to confirm. (Mercedes-Benz Operating Fluids)

Q: Is CHF 202 the same as CHF 11S?
A: They're different formulations in the same family, but manufacturer data says they're compatible and can be blended. If your car calls for MB 345.0, you can use either that meets the spec. (Fuchs)

Q: My fluid is green-what is it?
A: Many MB 345.0 central hydraulic fluids (like CHF 11S) are dark green. That's normal for ABC systems.

Q: My older SL500 (R129) needs convertible-top fluid. Which spec is that?
A: Those systems typically use ZH-M mineral hydraulic oil that meets MB 343.0-a different fluid from ABC's 345.0. Don't mix them. (Mercedes-Benz Bevo)

Q: Can I mix CHF 11S and CHF 202?
A: Yes-reputable lubricant makers note they're suitable for blending. Do not mix them with CHF 7.1, ZH-M (343.0), ATF, or brake fluid. (Fuchs, Petroleum Service Company)

Q: How often should I change ABC fluid and the filter?
A: Mercedes doesn't publish a set interval for ABC. However, Mercedes' technical training article explains why proactive fluid & filter service helps prevent costly repairs, since the fluid is hygroscopic and works under high pressure. Many technicians schedule periodic service based on mileage/time and fluid condition.

Q: My dash says "ABC - Visit Workshop". Can low or bad fluid cause that?
A: Yes. Low level or contaminated fluid can trigger warnings and cause poor ride or noise. The Mercedes StarTuned piece shows how dirty fluid and debris affect pumps, accumulators, and valve blocks-so check level and quality first, then diagnose.

Q: Where is the ABC fluid reservoir? How do I check it?
A: It's in the engine bay with a marked cap/dipstick. Follow the owner's manual for exact steps (ride height/engine state can matter) and only top up with the correct spec. (static.oneweb.mercedes-benz.com)

Q: Can I use brake fluid in the ABC or top system?
A: No. Brake fluid is a different chemistry. For ABC, use MB 345.0 central hydraulic fluid. For older soft-top hydraulics, use MB 343.0 ZH-M mineral oil. (Mercedes-Benz Operating Fluids, Mercedes-Benz Bevo)

Q: What if my fluid looks milky or foamy?
A: That's usually air or moisture in the fluid-bad for pumps and valves. A proper flush and filter replacement with the correct spec fluid is the fix.

Q: Is ABC the same as air suspension?
A: No. ABC is hydraulic, not air-spring based. It uses fluid pressure to control body motion. (Wikipedia)

Q: How should I dispose of old hydraulic fluid?
A: Collect it safely and take it to a used-oil recycling drop-off or household hazardous waste site. The EPA explains how to manage and recycle used oil. (US EPA)

Q: I'm not sure which SL generation I have. Where can I check?
A: The R129 (late 1980s-2001) and R230 (2001-2011) generations are described here; this helps match your car to the right fluid spec. (Wikipedia)