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I've read a lot of concerns over the reformulation of M1 0W-40 (the newer FS formula) and that it was prone to shear out of spec more easily than the old formula. I change my oil 2X per year every 5 to 6K miles on my '99 C4 996..
Attached is my first Blackstone report for an analysis of the newer blend and much to my happy surprise, everything looks good - maybe Mobil 1 0W-40 is still OK. At 6K miles the oil was still within spec for viscosity, albeit on the lower end. A little bit of fuel in the oil as my flashpoint is right at the limit, but not bad. UOA attached.
I've also attached the last two UOAs that the previous owner ran on Mobil 1 5W-40 at 200 miles and 2900 miles. This is the oil that a mutual friend and Porsche tech recommends in lieu of the M1 0W-40. The wear characteristics are pretty much identical considering the miles on the oil sample I submitted (6000) and the viscosity is pretty much the same. Based on this very limited data set, I'd say the 0W-40 is OK and certainly no better than the 5W-40 that costs quite a bit more.
Alright, I'll bite. So your thought is that you'll go against your mechanics recommendation until you damage your engine or prove him wrong? Seems like a pretty narrow data set to form any conclusions yet, especially during the winter.
No. I had put the 0W-40 in the car back in June before I read anything on the newer FS formulation and the subsequent concerns which have arisen. Upon learning of the new FS formulation i had some concerns that the test would come back well below spec for viscosity.
My only point was that there was some Internet hype over on BITOG about the new M1 0W-40 formulation and how it was prone to shear out of spec very quickly. My first test (yes, this is a very limited data set - not any sort of scientific study) showed that is stayed within spec and was VERY close to the 5W-40. M1 5W-40 is not available at the local DIY store (Advance, Pep Boys, Etc) so I was on the fence about ordering it on line vs. just running the 0W-40 that is available at any Walmart. Ultimately I chose the latter, but I felt good enough about these test results to not second guess the decision. Additionally, zinc and phosphorus were higher in the 0W-40 than in the 5W-40. I'm probably old-school on this, but I like to see those numbers close to or over 1000 if possible.
Also, this was also not a "winter test". This was 6 months from mid-June to mid-December and Christmas eve in Gainesville, FL was 80 degrees. We don't get winter.
Lastly, not to argue with expertise of my friend that's a Porsche tech, but a lot of mechanics (or people in general) base decisions on their own anecdotal observations without looking at real data. My goal was to present something more useful than "my car ran better on ABC than on XYZ."
I'll run another test when I change the oil again in June to look for consistency or possible trends. Admittedly there are MUCH better oils out there but I'm not seeing anything in the M1 0W-40 alarming.
My local Indy runs a large 996 race car group and specialty is water cooled cars. They only run Mobil One 0W40. Street or race they run same in all 996 cars.
Lots of reasons why.
In SoCal could run 5W40 or 5W50 but my shop said why. Run 0W40 year round race or street. M1 is a good oil. Not the best? Maybe, But if you change your oil every 12 months or 3k mi you could probably be fine running extra virgin olive oil in it.
I agree that Mobil 0-40 isn’t the best, but it’s good enough for most 996 owners on the street. I used to run Amsoil and other more expensive oils, but this engine is really geared for 0-40 given daily driving in all seasons. My car has 5 bar of hot oil pressure above 2500 RPM, even at 105C water temp, so going to a thicker oil doesn’t have benefits that I could tell.
I have not heard of too many negative UOA results for Mobil 1 0-40 on this engine. I run it also, and tracked the history of my car from the beginning and they used this oil from the start. I have 55k miles and no engine issues so far. I’ll probably just stick with what I’ve been doing so far. I have a completely original engine - original IMSB, water pump, AOS, everything stock. No oil usage, no smoke, pulls strong, been on the track twice and not concerned that the stock oil choice is a weak point on this engine design.
I agree that Mobil 0-40 isn’t the best, but it’s good enough for most 996 owners on the street. I used to run Amsoil and other more expensive oils, but this engine is really geared for 0-40 given daily driving in all seasons. My car has 5 bar of hot oil pressure above 2500 RPM, even at 105C water temp, so going to a thicker oil doesn’t have benefits that I could tell.
I have not heard of too many negative UOA results for Mobil 1 0-40 on this engine. I run it also, and tracked the history of my car from the beginning and they used this oil from the start. I have 55k miles and no engine issues so far. I’ll probably just stick with what I’ve been doing so far. I have a completely original engine - original IMSB, water pump, AOS, everything stock. No oil usage, no smoke, pulls strong, been on the track twice and not concerned that the stock oil choice is a weak point on this engine design.
I'm in complete agreement with you. My 99 C2 has 141K+ miles, runs Mobil 1 0W-40, has a LN oil filter full flow adapter and magnetic drain plug, run a Mobil 1 oil filter and change the oil/filter twice a year. I do not have any ticks, rattles or problems. I am totally comfortable with where the engine runs as my daily driver, and I'm not going to spend any time rethinking this formula. @55K I'm thinking you will be trouble free for a long time.
That is interesting that the Zinc and phosphorus are back up. I wish you had gotten the TBN done while you were at it though. Is it just the standard M1 you are using? On the sheer issue, my understanding is that it was only an issue on track at higher operating temps. A lot of the racers around here use the M1 15w-50 which in addition to being a racing oil has the added bonus of being available at Walmart.
The race shop I mentioned said the 15/50 oil can be a problem with variocams? Not much of a mechanic but I recall something about heavier, thicker oil affecting this.
The race shop I mentioned said the 15/50 oil can be a problem with variocams? Not much of a mechanic but I recall something about heavier, thicker oil affecting this.
Correct. 15w-50 is not recommended for these cars because it is generally too thick.
Cold (104F) viscosity of Mobil 1 15w-50 = 125
Cold (104F) viscosity of Mobil 1 0w-40 = 75
If one wanted to run 15w-50 for track days in the desert where ambient temps are 85+, I cannot imagine that there would be a viscosity problem as long as temps are well into the operating range (93C and above). It possibly also works fine even for cold start days at 10C and above). But at some point and temperature level, the oil will just be too thick and could cause problems, such as a frosty morning. And this 15w oil would also not bode well for people who drive their cars in the winter, such as cold starts well below -18C
Correct. 15w-50 is not recommended for these cars because it is generally too thick.
Everyone mentions the viscosity difference, but does anyone actually know if it is the chemistry difference between 0w-40 and 15w-50 and/or the viscosity difference that makes 15w-50 not an "A40" approved oil?
Everyone mentions the viscosity difference, but does anyone actually know if it is the chemistry difference between 0w-40 and 15w-50 and/or the viscosity difference that makes 15w-50 not an "A40" approved oil?
I’m making the assumption that since there are dozens of brands and styles of oil on the approved oil list, that these different brands and styles would have different properties. Yet they are all very similar with their viscosity labels. I’m also assuming that there are larger differences in makeup between some oil types of the same viscosity, versus same brand and similar styles having different viscosities.
Note: Mobil 1 is ranked quite high (favorable) on the list as well. I don’t take any one single blog post as truth, but rather, gather as much data across as many sources as possible to get closer to the truth. Like I said, I haven’t really seen anything bad about Mobil 0w-40.
There also the -40F oil flow “test” that was done on Youtube here comparing only 4 brands:
Again, it’s not scientific, but you can be sure I won’t be running oil that doesn’t flow well at cold temps in my engine. I recently performed a cold start at -10F and felt confident in having chosen 0w-40 oil.
Last edited by Mike Murphy; 01-12-2018 at 10:37 AM.
Update of most recent UOA, for interested parties. I know DT-40 is the current forum favorite. But I'm still liking what I see in the M1 0W-40 for now.
12-22-2017, 12:57 PM
UOA M1 0W-40 FS Formula
