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I do not disagree with anything you say except your dismissal of pkalhan’s point by discounting the extent to which engineering and material choice (the use of Lokasil, Alumsil, tight piston to sleeve clearances, etc.) contributes to the problem as explained by Mr. Navarro. While proper maintenance and driving (which I frankly assume as a given among the members of this forum) could be a contributing cause, one can avoid the potential engineering defects by getting a 92A engine as pkalhan suggests. It is a reasonable conclusion on his part given the known facts and science discussed above…..even if that statement offends some 991.1 owners …….of which I am a member.
I guess we can agree to disagree. Engineering defects exist with every car. The 991.2 included. It’s not about being offended. It’s about thoughtful risk consideration.
His own website notes that proper maintenance prevents bore scoring. And again, there isn’t statistical significance in this thread or any other to conclusive show this is a common problem. At least in my field, that means a large enough sample size.
So it’s reasonable enough for me to conclude that with proper maintenance, the risk isn’t that high until there is further data. And that is unlike other engineering defects in other cars that has a high chance of failure even with proper maintenance and can only be prevented with actual modification.
SUMEbore (or any of the similar thermal spray technologies like transfer wire) is very expensive -- even in mass production. But there is a reason that Porsche moved to it. If bore scoring was "statistically insignificant" on this platform then Porsche could have and would have saved the money and stayed with Alusil cylinders.
Charles' paper never says proper maintenance prevents bore scoring -- it says running a "good" oil (not M1 0W-40 like Porsche recommends) at short OCIs will give you the best odds to. There is more than a large enough sample size, you just don't have access to the data. Very few people in the aftermarket do but Charles would because he rebuilds these engines so can see what comes in the door. He just spelled it out again in his last post above: "That said, like I've said before, the failure rate is much lower for the MA1 engine than its predecessor, but as the cars age, I expect to see more issues. 10 years ago it was mostly IMS bearing failures that was taking out M96 engines and now it's almost 100% bore scoring failures." You can't expect to get any better information than that.
To Charles' point: When I bought my first Porsche 911, a 996, 15+ years ago people "in the know" were dialed into IMS failures........no one really talked about bore scoring. D chunks on the early water cooled engines....not bore scoring. Fast forward to today, boy have things changed......
SUMEbore (or any of the similar thermal spray technologies like transfer wire) is very expensive -- even in mass production. But there is a reason that Porsche moved to it. If bore scoring was "statistically insignificant" on this platform then Porsche could have and would have saved the money and stayed with Alusil cylinders.
Charles' paper never says proper maintenance prevents bore scoring -- it says running a "good" oil (not M1 0W-40 like Porsche recommends) at short OCIs will give you the best odds to. There is more than a large enough sample size, you just don't have access to the data. Very few people in the aftermarket do but Charles would because he rebuilds these engines so can see what comes in the door. He just spelled it out again in his last post above: "That said, like I've said before, the failure rate is much lower for the MA1 engine than its predecessor, but as the cars age, I expect to see more issues. 10 years ago it was mostly IMS bearing failures that was taking out M96 engines and now it's almost 100% bore scoring failures." You can't expect to get any better information than that.
To Charles' point: When I bought my first Porsche 911, a 996, 15+ years ago people "in the know" were dialed into IMS failures........no one really talked about bore scoring. D chunks on the early water cooled engines....not bore scoring. Fast forward to today, boy have things changed......
people seeking out Charles' expertise aren't exactly a random sample of the population, though. so again, we really don't have any "data" and as much as anecdotes are effective at telling a story, multiple anecdotes still aren't data.
"So it’s reasonable enough for me to conclude that with proper maintenance, the risk isn’t that high until there is further data. And that is unlike other engineering defects in other cars that has a high chance of failure even with proper maintenance and can only be prevented with actual modification."
Key point here is the "for me". If you are cool with it so be it. People different risk tolerances. I obviously have a lower risk tolerance than you. Even though the chances may be low, I would not be saying "Oh ***** feathers" if I needed an engine rebuild. I would be kicking myself for not listening to my gut and buying the newer model. So, for me, I would rather just stick with the 991.2 or newer.
people seeking out Charles' expertise aren't exactly a random sample of the population, though. so again, we really don't have any "data" and as much as anecdotes are effective at telling a story, multiple anecdotes still aren't data.
Most of the facts that we operate on in life are formed by anecdotes so I don't really understand your point. In the hard sciences, all "facts" are fundamentally considered provisional. Multiple what you are calling anecdotes, when given by a professional who is seeing these engines day in and day out, is what you use to form "fact". Please remember that these engines are still quite new and therefore even in the aftermarket there has been limited information compared to previous generations. I manage risk professionally for a living. If you talk to a trader and they tell you that a, b, c traded for x, y, z those are "anecdotes" but can be used to form a reliable picture and that is exactly what professionals do.
Wonder if Porsche would take some sort of remedial action, or at least send some warning, if this is any sort of concern for 991.1 owners now surfacing years later from a liability standpoint?
Most of the facts that we operate on in life are formed by anecdotes so I don't really understand your point. In the hard sciences, all "facts" are fundamentally considered provisional. Multiple what you are calling anecdotes, when given by a professional who is seeing these engines day in and day out, is what you use to form "fact". Please remember that these engines are still quite new and therefore even in the aftermarket there has been limited information compared to previous generations. I manage risk professionally for a living. If you talk to a trader and they tell you that a, b, c traded for x, y, z those are "anecdotes" but can be used to form a reliable picture and that is exactly what professionals do.
my point is the actual failure rate is probably orders of magnitude below a person's perception from reading forums.
Greater burn-off than other oils of the same grade.
Piston-slap observed/noted with long-term use.
Increased valve noise compared to oils of the same grade.
Greater thinning-out/inability to stay-in-grade during use.
Poor performance on the Timken test (tri-synth)
In my 997.2 with Mobil it use to burn about ~1 quart every 1,000 miles. Then I switched to Motul 8100 5W-40 xcess, didn't burn a drop, ran quieter, and felt smoother. 991 since day 1 Motul 5w-40, doesn't burn a drop, runs like velvet smooth brand new motor.
AFAIK, the four ball wear test is ideal for measuring grease, not oil. I don't think it's a valid way of measuring how good an oil is. It's like saying that petroleum jelly is better than hand lotion because it's thicker.
AFAIK, the four ball wear test is ideal for measuring grease, not oil. I don't think it's a valid way of measuring how good an oil is. It's like saying that petroleum jelly is better than hand lotion because it's thicker.
Good job on digging back almost three years into this thread.
That chart above would be more interesting - nothing withstanding any opinions on the test methodology - if the Mobil product tested was the same formulation that carries A40 designation rather than a random oil from Mobil’s second-best (or third-best) product line.
In the attached used oil analysis which includes data on both Mobil 1 0W-40 and Motul 8100 Xcess Gen2, you’ll notice that after 4K miles on the Mobil 1, the Viscosity index was 11.8. 12.6 is the minimum threshold for a 40 weight oil and M1 in virgin oil analysis is shown to start at 12.9 centistokes. That means from the start, Mobil 1 barely meets the description of a 40 weight oil. It is very thin from the start in order to improve fuel economy (which is what the factory likes to have sit up there for their CAFE standards). After 4K miles, the analysis shows that the viscosity index went down to 11.8 which means the oil has fallen out of grade from a 40 weight to a 30 weight oil. This is not great and perhaps why the metal wear numbers were up significantly over the Motul which had almost 5K miles on it. After 5K miles, the Motul’s viscosity index held at 13, so still a 40 weight oil. It did not shear out of viscosity. I’m no longer a Mobil 1 fan.
Last edited by Carreralicious; 01-10-2023 at 09:51 AM.
AFAIK, the four ball wear test is ideal for measuring grease, not oil. I don't think it's a valid way of measuring how good an oil is. It's like saying that petroleum jelly is better than hand lotion because it's thicker.
This is not necessarily correct. With respect to the four ball wear test, ASTM D-2266 is for grease and ASTM D-4172 is for oils.
In the attached used oil analysis which includes data on both Mobil 1 0W-40 and Motul 8100 Xcess Gen2, you’ll notice that after 4K miles on the Mobil 1, the Viscosity index was 11.8. 12.6 is the minimum threshold for a 40 weight oil and M1 in virgin oil analysis is shown to start at 12.9 centistokes. That means from the start, Mobil 1 barely meets the description of a 40 weight oil. It is very thin from the start in order to improve fuel economy (which is what the factory likes to have sit up there for their CAFE standards). After 4K miles, the analysis shows that the viscosity index went down to 11.8 which means the oil has fallen out of grade from a 40 weight to a 30 weight oil. This is not great and perhaps why the metal wear numbers were up significantly over the Motul which had almost 5K miles on it. After 5K miles, the Motul’s viscosity index held at 13, so still a 40 weight oil. It did not shear out of viscosity. I’m no longer a Mobil 1 fan.
Wow, that is a fantastic result on your last UOA and the numbers appear almost too good to be true! I was using 0w40 with decent results but decided to experiment with M1 5w40 to correct the viscosity and have been happy so far. In a recent Lake Speed video he expresses concern over the high calcium content of an M1 0w40 sample (3,000+) and it's connection with LSPI ( Low speed pre ignition). I don't believe I've ever experienced it and I never lug my engine but I don't believe I've seen an A40 oil with calcium numbers as low as yours.
That's not Lake's concern in that LSPI is well documented in tribological literature especially for turbocharged direct injected engines. Avoid oils containing high levels of Calcium and eliminate Sodium. The detergent package and additives utilized in the oil you choose matters very much including other important considerations like the soot dispersant (DFI engines produce soot similar to a light diesel engine). Calcium is the most widely used quite frankly because it's cost effective ("cheap"). There are much better oils than the M1 products.
Wow, that is a fantastic result on your last UOA and the numbers appear almost too good to be true! I was using 0w40 with decent results but decided to experiment with M1 5w40 to correct the viscosity and have been happy so far. In a recent Lake Speed video he expresses concern over the high calcium content of an M1 0w40 sample (3,000+) and its connection with LSPI ( Low speed pre ignition). I don't believe I've ever experienced it and I never lug my engine but I don't believe I've seen an A40 oil with calcium numbers as low as yours.
To be clear, that is not my UOA…I saw that from another forum member when they posted their results. I saw that and decided to switch to Motul and am happy with the oil so far. I haven’t done a UOA yet but I’ve noticed it already burns about 50% less than the Mobil 1 I had in the car before (and I had the 5W-50 in my car which is even a thicker oil than the Motul).
Last edited by Carreralicious; 01-10-2023 at 12:27 PM.
01-07-2023, 01:12 AM
