- GM is replacing Supercar oil with FS 0W-40 in recalled L87 V8.
- Both oils share viscosity but differ in chemistry and purpose.
- FS may slightly boost wear protection over cleaning power.
General Motors just made a small but interesting change regarding its problematic L87 V8, an engine at the center of several lawsuits. Last year, it recalled some 600,000 vehicles in the U.S. over the motor, and now, we’re learning about a new bulletin sent to dealers addressing it.
That recall itself followed a federal investigation triggered by tens of thousands of owner complaints, which helps explain why even minor updates are now getting close attention.
More: GM’s V8 Is Fueling Lawsuits Faster Than Ford Can Issue Recalls
Up until now, part of the recall remedy was to use Mobil 1 Supercar 0W-40 oil. Now, dealers will switch to Mobil 1 FS 0W-40. Yes, that change is significant.
The issue with these engines is that they might have rod bearing contamination and or crankshafts that don’t meet specifications. Vehicles that fail inspection get a new engine, and those that pass get new oil.
More: Did GM Know Your V8 Was Doomed?
According to GM Authority, the switch from Supercar to FS comes down to cost and availability. Supercar costs more and is harder to find. FS is more readily available and less expensive. While they’re very similar, there are some key differences.
Brian Silvestro over at The Autopian did a great job of breaking down their unique properties. While both oils share the same 0W-40 viscosity rating, they’re aimed at different audiences. Mobil 1’s Supercar blend is explicitly marketed toward high-performance applications, with Mobil calling out Corvettes and Camaros by name.
It’s designed to handle track use and aggressive driving, even if it’s also approved for daily duty. The FS blend, by contrast, is positioned as a more well-rounded option. Mobil describes it as suitable for a wide range of gasoline and diesel engines, emphasizing durability across “mild to extreme” driving conditions rather than outright performance.
Read: Drivers Say GM Fixed Their V8s, But The Engines Still Died
While it doesn’t provide specific blend details, it does give us information as to what goes into each product. The FS blend reportedly contains slightly higher levels of phosphorus and zinc than the Supercar oil.
Both are key anti-wear additives, with zinc-based compounds like ZDDP forming a protective film on metal surfaces to reduce friction and component wear. That suggests the FS oil may offer marginally better protection under load.
