- Joined
- May 21, 2024
- Messages
- 8
Long time lurker, first time poster here. I've gone WAY down the rabbit hole and feel like I can't find a solution in the maze of information I've uncovered, so I'm hoping to get some insights from others here. I'll try and be as clear as possible with my situation and my questions.
The car in question is an unmodified 2015 BMW M5 (F10). It's located in SE England, so the climate is relatively mild with no extreme heat or cold. The car is garaged and not a daily driver; it covers about 2,000 miles per year at best. Due to being garaged, it is not typically started in below freezing conditions. The car is used for longer journeys and some spirited driving, but is not tracked. I do not need to top off the oil between changes, which is actually quite rare for the S63 engine, as burning through a liter is not unusual. I will change the oil annually regardless of mileage.
Overarching Concern: The engine is widely known to eat con rod bearings and grenade, so having too thick of an oil could exacerbate this issue at start up. However, the engine can also can run very hot, so having a thinner oil to protect rod bearings at cold start may not be sufficient to protect the engine at higher temps.
The owner's manual recommends either 0W-30 or 0W-40. However, these viscosity levels have different properties, so this is not actually helpful, IMO. If you go to a dealership in the UK, they will fill it with 0W-30. In the US, BMW LL-01 spec is used, while in Europe LL-04 is used due to the lower sulfer content in our fuel. Many M5 guys seem to use a 5W-40 weight oil, or even thicker, with the rationale that the S63TU runs very hot and needs something thicker than a 0W-30 for proper protection. This leads me to my first few questions:
Question 1: If the fuel available is low sulfer, is it better to run a lower SAPS oil (like the LL-04 spec)? I know lower SAPS is better for the emissions system, but this aside, does a higher SAPS oil provide better engine protection? It seems that most 5W-40 oils are higher SAPS, so if I run this viscosity then it will be with a LL-01 spec. I've also read that with direct injected engines, a lower SAPS oil can help reduce carbon build up on the valves, but I'm not sure how much truth there is to this.
In my last oil change, I decided to increase the oil viscostiy a bit from 0W-30 to 5W-30, choosing to use Ravenol VMP. With all this new research I've done, I'm now wondering if I should be increasing viscosity yet again. Where I get hung up is when I start comparing the mm²/s figures for viscosity at 40C and 100C. The Ravenol VMP 5W-30 is 66.3 and 11.9, respectively. If I stay with Ravenol and look at their VST 5W-40, the figures are 79.4 and 13.5.
Question 2: In cold start conditions, is there a material difference in how the oil would behave (or how quickly it would lubricate rod bearings) when looking at the 5W-30 and 5W-40 figures above (66.3 vs 79.4)? Similarly, at hot temps, is there a material difference in how they would protect the engine (11.9 vs 13.5)?
Thank you in advance for any guidance you are willing to share.
The car in question is an unmodified 2015 BMW M5 (F10). It's located in SE England, so the climate is relatively mild with no extreme heat or cold. The car is garaged and not a daily driver; it covers about 2,000 miles per year at best. Due to being garaged, it is not typically started in below freezing conditions. The car is used for longer journeys and some spirited driving, but is not tracked. I do not need to top off the oil between changes, which is actually quite rare for the S63 engine, as burning through a liter is not unusual. I will change the oil annually regardless of mileage.
Overarching Concern: The engine is widely known to eat con rod bearings and grenade, so having too thick of an oil could exacerbate this issue at start up. However, the engine can also can run very hot, so having a thinner oil to protect rod bearings at cold start may not be sufficient to protect the engine at higher temps.
The owner's manual recommends either 0W-30 or 0W-40. However, these viscosity levels have different properties, so this is not actually helpful, IMO. If you go to a dealership in the UK, they will fill it with 0W-30. In the US, BMW LL-01 spec is used, while in Europe LL-04 is used due to the lower sulfer content in our fuel. Many M5 guys seem to use a 5W-40 weight oil, or even thicker, with the rationale that the S63TU runs very hot and needs something thicker than a 0W-30 for proper protection. This leads me to my first few questions:
Question 1: If the fuel available is low sulfer, is it better to run a lower SAPS oil (like the LL-04 spec)? I know lower SAPS is better for the emissions system, but this aside, does a higher SAPS oil provide better engine protection? It seems that most 5W-40 oils are higher SAPS, so if I run this viscosity then it will be with a LL-01 spec. I've also read that with direct injected engines, a lower SAPS oil can help reduce carbon build up on the valves, but I'm not sure how much truth there is to this.
In my last oil change, I decided to increase the oil viscostiy a bit from 0W-30 to 5W-30, choosing to use Ravenol VMP. With all this new research I've done, I'm now wondering if I should be increasing viscosity yet again. Where I get hung up is when I start comparing the mm²/s figures for viscosity at 40C and 100C. The Ravenol VMP 5W-30 is 66.3 and 11.9, respectively. If I stay with Ravenol and look at their VST 5W-40, the figures are 79.4 and 13.5.
Question 2: In cold start conditions, is there a material difference in how the oil would behave (or how quickly it would lubricate rod bearings) when looking at the 5W-30 and 5W-40 figures above (66.3 vs 79.4)? Similarly, at hot temps, is there a material difference in how they would protect the engine (11.9 vs 13.5)?
Thank you in advance for any guidance you are willing to share.