- Joined
- Feb 2, 2026
- Messages
- 6
Looking for some oil recommendations for a recently acquired M120 V12.
The car is a 1999 SL600 with about 80,000 miles. It spent roughly six years in storage before I bought it, but it’s been coming back to life nicely. Under the oil cap the aluminum is very clean and bright with essentially no varnish or sludge.
The owner’s manual lists quite a few acceptable viscosities, including 0W-40, 5W-40, 5W-50, and even some 30-weights depending on ambient temperature. Since the engine is now nearly 30 years old, I’m curious what people here would actually run rather than just what the manual allows.
The car won’t see a ton of miles, but when I do drive it, it won’t be babied. I’m planning on a conservative 3,000-mile OCI simply because of the engine’s age, even though I know many modern oils can go much longer. If a UOA comes back exceptionally clean, I’d consider extending it to around 5,000 miles.
Oils I’ve been considering include Driven DT40, HPL, Mobil 1 ESP X4 0W-40, or another high-quality Euro formulation. I’d also be interested in hearing whether anyone thinks a quality synthetic blend would be more than sufficient at a 3,000-mile OCI.
For those familiar with the M120, what oil would you choose today, and why? Would you stick with a 40-weight, move to a 50-weight as the manual permits, or even consider one of the approved 30-weights?
The car is a 1999 SL600 with about 80,000 miles. It spent roughly six years in storage before I bought it, but it’s been coming back to life nicely. Under the oil cap the aluminum is very clean and bright with essentially no varnish or sludge.
The owner’s manual lists quite a few acceptable viscosities, including 0W-40, 5W-40, 5W-50, and even some 30-weights depending on ambient temperature. Since the engine is now nearly 30 years old, I’m curious what people here would actually run rather than just what the manual allows.
The car won’t see a ton of miles, but when I do drive it, it won’t be babied. I’m planning on a conservative 3,000-mile OCI simply because of the engine’s age, even though I know many modern oils can go much longer. If a UOA comes back exceptionally clean, I’d consider extending it to around 5,000 miles.
Oils I’ve been considering include Driven DT40, HPL, Mobil 1 ESP X4 0W-40, or another high-quality Euro formulation. I’d also be interested in hearing whether anyone thinks a quality synthetic blend would be more than sufficient at a 3,000-mile OCI.
For those familiar with the M120, what oil would you choose today, and why? Would you stick with a 40-weight, move to a 50-weight as the manual permits, or even consider one of the approved 30-weights?
