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CAVEAT - I do not use DT 40 myself, but this is the old formula for DT 40 from 2017. Current formula for DT 40 has much higher Moly. Just an FYI for readers.
I have always used M1 0W-40. This next change next week I am going to use Motule 5W-40. I live in NH. I am thinking of using the M1 during Fall and Winter and Motule for summer and spring.
does this sound reasonable?
2013 C2S. 33,000 miles DD all year round.
Interesting discussion and we're all trying to share knowledge as we have a common interest in these fine cars. An engineer with a degree in Tribology once told me the ideal cSt at 100C for bearings was around 10. Much higher than this created drag and parasitic load. Much lower than this created boundary lubrication issues. Porsche has tested this to the nth degree, which is likely why they are happy with 0W-40. They have a thorough understand of how 0W-40 behaves and a valuable alliance agreement with Mobil but have a long list of other approved brands. As others have noted 5W-50 is also approved and I'm sure it offers great attributes, however, with the trade off of slightly slower circulation at start-up and higher parasitic loss at temperature (perhaps a non-issue to some). To me, finding the sweet spot between power and protection is the key. I'm not stuck on a particular brand but, as I stated in my original email, Motul X-Cess 5W-40 offered me the same variable oil pressures as Mobil 1 0W-40 with the additional benefits of lower start-up noise and no need for top-up after hard runs.
Interesting discussion and we're all trying to share knowledge as we have a common interest in these fine cars. An engineer with a degree in Tribology once told me the ideal cSt at 100C for bearings was around 10. Much higher than this created drag and parasitic load. Much lower than this created boundary lubrication issues. Porsche has tested this to the nth degree, which is likely why they are happy with 0W-40. They have a thorough understand of how 0W-40 behaves and a valuable alliance agreement with Mobil but have a long list of other approved brands. As others have noted 5W-50 is also approved and I'm sure it offers great attributes, however, with the trade off of slightly slower circulation at start-up and higher parasitic loss at temperature (perhaps a non-issue to some). To me, finding the sweet spot between power and protection is the key. I'm not stuck on a particular brand but, as I stated in my original email, Motul X-Cess 5W-40 offered me the same variable oil pressures as Mobil 1 0W-40 with the additional benefits of lower start-up noise and no need for top-up after hard runs.
I wasn't familiar with Tribology so my mind immediately went here.
Here are the M1 0w40 numbers from my 30k mi 991.1 3.4 Carrera which seem fine to me and for my short drain interval use case. There is a lot of negativity for M1 0w40 particularly it's low viscosity and tendency to sheer but when I compare it to these Motul X-cess and Driven DT-40 numbers posted above I'm failing to see why many consider them to be superior. Even with the noticeable bump in viscosity the DT-40 does not appear to reduce wear in any appreciable way. I have also followed the Lexvan M1 5w50 thread and considered experimenting with the 5w50 as it does provide a noticeable bump in viscosity but remain unsure of if or how the increased viscosity will reduce wear or further protect my engine.
Motul 8100 has no Moly in it, whereas the Mobil products do. I know that’s not the only anti wear additive that works in these formulations but can’t see how it hurts, so I asked Motul both in this forum and to their general website as to why they don’t include any in their formulation. Never got a response so I stick with Mobil 5W-50, as I want to continue to use an A40 approved oil.
I asked ExxonMobil questions about their oil, and they did answer. Just sayin.
Last edited by Carreralicious; 05-14-2021 at 11:27 AM.
All you touting Motul 5-40 do have UOAs and have you compared the wear metals to other oils/UOAs? I have been using it for the last 4 changes and I am just (disappointingly) realizing my wear metals are typically consistently higher when compared to other oils/UOAs. I will be adding Ceratec and see if this helps and which will be evidenced by my next oil change's UOA. This is however on a 997, YMMV.
BTW I thought LN recommends DT-40 (which I will be switching to on my next oil change based on UOA results I have seen and compared)
Carry on ...
I use the 8100 Xcess Gen2 5w40 in my 108k 996 C4s. I use it in combination with Liqui Moly MoS2. Having the oil tested after 2 oil changes the results are great. I'd converted from Mobil1 A40 that had been used over the vehicle's life.
Having moved and run out of Motul I had to use Mobil1 again in a pinch, there's a noticeable difference in the engine. I switched back to Motul as soon as I was able to source it.
05-12-2021, 10:31 PM
