I felt an irresistible urge to delve into a bit of research concerning the latest oil specifications for the Porsche C40. My primary area of interest lies in the 4.0-liter engines (9A2 Evo and 9A1.5) equipped with particle filters, including the GTS 4.0, GT4, and 992 GT3 models. It’s worth noting that first two models demand 8 liters of oil during an oil change while the Porsche 992 GT3’s recommended oil change interval involves only 4 liters of oil. Now, Porsche recommends Mobil and they keep reminding you that with little stickers on the hood. They partnered up many years ago and that’s fine. Opening the 718 GT4 user manual on page 98 surprises us with Mobil logo and a little table mentioning oil grades.
The theory
As you can see oil specification C40 / VW 511 00 is required. C40 is not backwards compatible with older engines requring A40, C30 or C20. In theory one can choose any oil that meets the required grade and specification. Easy? Not quite … There exist official lists that inform us about the brands and models that have been officially approved. When we review the list released by Porsche North America, we can identify 16 different brands that have valid factory approvals (the validity of some approvals lasts until 06/2024). When we shift our attention to a European Approval document provided by dealers, we find that only one brand and model has been granted approval: Mobil ESP X3 0W-40.
Approval lists
Quite intriguingly, the user manual permits the use of the 5W-40 grade oil when specific temperature conditions are met. Upon consulting various European dealers, it became evident that only a small number confirmed the authorization of using any C40-approved oil. In contrast, the majority emphasized the exclusive suitability of Mobil ESP X3. Curiously, they did not address the question of why the user manual permits a grade for which Mobil lacks a corresponding product. The question remains unanswered, as the European approval list (Freigabe) exclusively features one brand, whereas the US approval list provides distinct worldwide validity dates for each product.
A40 vs. C40
The C40 specification is likely required due to the presence of gasoline particulate filters (GPF) in the engines, although not all new Porsches are equipped with them. Within the USA market, there are some models that do not feature GPFs yet they still requite the use of the C40 oil. A comparison chart reveals that the C40 is low SAPS oil with reciudes content of sulfated ash. It is clear tha C40 has higher deposit and emissions protection requirements.
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| Specification/Oil | Ravenol RUP |
Mobil X3 ESP |
Motul X-clean G2 |
|---|---|---|---|
| Viscosity | 5W-40 | 0W-40 | 5W-40 |
| Datasheet | |||
| Technology | Full Synthetic PAO | HC Synthetic | HC Synthetic |
| Specification | Acea C3, API SN | Acea C3, API SN | Acea C3, API SN |
| C40 Recommendation | Yes | Yes | Yes |
| C40 Approval in EU | No | Yes | No |
| C40 Approval in US | Yes? | Yes | Yes? |
| Density (kg/m³) | 846 (20 °C) | 846 (15,6 °C) | 847 (20 °C) |
| Viscosity at 100 °C (mm²/s) | 14,3 | 14,1 | 13,5 |
| Viscosity at 40 °C (mm²/s) | 87,5 | n/a | 77,1 |
| HTHS Viscosity at 150 °C (mPa*s) | 3,9 | 3,8 | 3,9 |
| Viscosity index | 169 | n/a | 180 |
| Pourpoint (°C) | -51 | -48 | -42 |
| Flashpoint (°C) | 244 | 230 | 230 |
| Noack Volatility (% M/M) | 6,0 | n/a | n/a |
| tbn (mg KOH/g) | 8,3 | n/a | 8,0 |
| Sulphated Ash (%wt.) | 0,8 | n/a | 0,8 |
The date confusion
The only theory that makes at least some sense (ans was proposed by a couple of dealers) is that the mentioned list is valid for vehicles from the year 2020 onwards, as indicated in the list. But then again, why are the approvals still valid? And why the 5W-40 grade is suggested in the user manual? Why don’t they simply withdraw all other oil brands, as is done in the European document, where only one brand is available?
Verdict
Despite those facts, I’m currently inclined toward choosing Ravenol. It boasts remarkably similar physical specifications to Mobil, particularly in terms of density, but what’s most crucial to me is its superior oil film stability, coupled with the fact that it’s a fully synthetic group IV oil. Additionally, I find it somewhat disconcerting that Mobil lacks certain vital specifications like TBN (Total Base Number) and sulfated ash content.
