[DrewNewM2]

You all comfortable only changing the oil once per year to get the included (free) oil changes? I will barely be hitting 3k-4K miles per year. My car is stock. A year seems like a long time. I change the oil on my modified Subbie every 6 months and that car only sees about 2-3k miles. I was thinking of doing it every 6 months but it’s extra $$$. If I modify/tune the G87 I will definitely increase frequency of changes and probably oil type.

[BroDoze]

Stock interval is fine. Heavily modded and/or thrashing the car constantly, definitely increase frequency.

[RockCrusher]

Originally Posted by DrewNewM2

You all comfortable only changing the oil once per year to get the included (free) oil changes? I will barely be hitting 3k-4K miles per year. My car is stock. A year seems like a long time. I change the oil on my modified Subbie every 6 months and that car only sees about 2-3k miles. I was thinking of doing it every 6 months but it’s extra $$$. If I modify/tune the G87 I will definitely increase frequency of changes and probably oil type.

When you use your M2 do you drive it long enough that the engine (coolant and oil -- remember oil temperature lags coolant temperature) gets fully up to temperature?

If yes then once a year oil/filter service is (probably) ok.

I say probably because an oil analysis might find the oil has experienced some degree of degradation that could justify an early oil/filter service. (More on oil analysis below.)

Also, I do not know how the condition based service (CBS) system would behave. If your 3K/4K miles a year consisted of short trips or other usage that could be considered harsh or severe the CBS system might alert an oil/filter service is due before one year rolls around.

Obviously if the CBS system alerted you a service is due that over rules my opinion you could go a year of 3K/4K miles of driving between oil/filter services.

Regarding oil analysis... At ~620 miles I had the oil analyzed from my 2024 230ix along with a sample of the virgin oil the tech was using to refill the engine.

What the analysis turned up is in 620 miles the factory fill oil had lost 1+ point in its 100C viscosity index.

Old oil: Viscosity at 100C: 7.373
New oil: Viscosity at 100C: 8.577

Based on the results of that oil analysis I'm tempted to have my M2 in with around 10,500 miles on the odometer and around 3200 miles since the last oil/filter service to have the oil/filter service done and have the tech capture an old oil sample and a new oil sample that I can have analyzed.

From the results of the analysis I think I can make an informed decision if early oil changes are called for or not called for. At least based on my usage.

[chris719]

Originally Posted by DrewNewM2

You all comfortable only changing the oil once per year to get the included (free) oil changes? I will barely be hitting 3k-4K miles per year. My car is stock. A year seems like a long time. I change the oil on my modified Subbie every 6 months and that car only sees about 2-3k miles. I was thinking of doing it every 6 months but it’s extra $$$. If I modify/tune the G87 I will definitely increase frequency of changes and probably oil type.

I agree with the above, time is not really an issue as long as you aren't doing 100% short trips and leaving tons of fuel and moisture in the oil.

[chris719]

Originally Posted by RockCrusher

What the analysis turned up is in 620 miles the factory fill oil had lost 1+ point in its 100C viscosity index.

Old oil: Viscosity at 100C: 7.373
New oil: Viscosity at 100C: 8.577

When you sample next, if you are using Blackstone I recommend you switch to OAI (Horizon) or Polaris. Blackstone seems to be very far off sometimes on simple kinematic viscosity measurements, they also do not give you an actual fuel measurement but just an estimate inferred from flashpoint. Horizon uses GC to give you an actual measurement.

Your rapid drop in viscosity is pretty typical. I've noticed the same behavior from M1 0W-40, ESP 0W-30, etc. They tend to stabilize though. Some of the "shear" may be intentional to counteract oxidative thickening over long intervals.