Been running 0W-40 Mobil 1 FS European Car Formula for 2 weeks now



Mobil has reformulated their line up recently. This video focused specifically on the 0W-40 oil and has been posted multiple times on this forum already.
 
On BMW M20 and M30 engines I’ve owned, cold engine piston slap noise was noticeably different between brands, even with the same weight. The M20 had some warm also, less difference between brands when warm.
I won’t go into motorcycle engine noises changing with brand.
Lots of guys here like to throw shade quickly, but it’s always clear to me at least, they have less real world experience. When you have seen lots of things in the real world that are puzzling to you, it tends to temper your enthusiasm for calling this stuff out too quickly.
 
Well now that you mention it, that is an interesting topic. I had been running Fram Ultra filters exclusively but this last oil change I went to Wix XP. But, with that being said I would get 85psi oil pressure with the Fram filters within 1-2 seconds so I don't think that was the issue.

The sounds I'm attributing to piston slap is the sound I would get only when going out to start the car first thing in the morning. Not really concerned with it, I knew I would have it going into the build. I just found it interesting I can no longer hear it.
My point was. Everything can be a factor. One factor can change everything.
 
My car is a fully built "racing" motor with forged internals and looser tolerances than factory. The first thing I really noticed which is a rather big difference is that before with either Penzoil Ultra, Rotella, or VR1 in anywhere from 5W-40 to 10W-30 I would have rather loud cold start with piston slap until the motor got up to temperature some and the metal parts had time to expand.

For some reason with this Mobil 1 0W-40 EU formula my motor has no piston slap that I can hear at all and overall the motor is much more quiet. I did not expect this at all...

Oh and my Moroso oil pan leaks A LOT more with this Mobil 1 than the other brands. In it's defense though I am using a different nylon washer so maybe that is the problem. We will find out next oil change.
For a race motor and off-the-shelf oil, I’d prefer to use M1 ESP X3/X4 0W-40 as it has a higher HTHS (3.8) and holds its viscosity better. It’s the current Porsche oil.
 
For a race motor and off-the-shelf oil, I’d prefer to use M1 ESP X3/X4 0W-40 as it has a higher HTHS (3.8) and holds its viscosity better. It’s the current Porsche oil.

It's almost 3 times as expensive and I change my oil roughly 2,000 miles.
 
It could be valve train noise from excessive lifter leak down with the thinner oil.
Tappet clatter and piston slap almost sound the same.

It's a B series Honda motor which is flat tappet. Maybe I should pop the valve cover to check valve lash.

Still, why would the noise go away with this oil?
 
Actually, it was available in the F series trucks for most of its run; from the 70s all the way until 1996 when that generation of F series trucks ceased.

The 300 six / 4.9L in F-150s never had a problem with improperly sized pistons, nor did it ever have forged parts.

My point was that ONLY the HD version of the 300 I-6 had forged internals, and that engine was ONLY put into the F600, F700, F800 chassis for dump trucks, box trucks, grain trucks, etc. The HD 300 I-6 was never fitted into an F150. By the time Ford was calling it by its metric name ("4.9L") that engine didn't have forged internals nor did it have piston size/bore issues. Whatever noise he's hearing likely isn't "piston slap".
I had a 95 F150 4wd Flareside and never experienced piston slap like my Honda. All I used in that truck was M1 10w30 and Pureone Filters. The only reason I sold it was because the frame was basically eaten out from all the rust. That engine was a beast, my dad also had 83 F100 and 87 F150 with it. They are actually quite hard to kill, the 83 actually went through 2 motors because the first one dumped too much gas and threw a rod, the 2nd one was basically used junk that someone put together and didn't last long either.
 
It's a B series Honda motor which is flat tappet. Maybe I should pop the valve cover to check valve lash.

Still, why would the noise go away with this oil?
Good question. You’re going to hear some valve train noise because of mechanical lifter clearance and that cannot be adjusted out.
Same goes for forged pistons or cast pistons that have been fitted with more than about .003” clearance.
 
I'm gonna stop you right there.

The only two things which generally cause "piston slap" are:
- improperly sized pistons to the bore
- forged pistons (which expand from warming up at a slow rate relative to the other components)
The F150 never had 4.9L engines which had either, in the 31 year run (1965 to 1996).

Whatever noise you're hearing, I seriously doubt it's "piston slap".


NOTE: The late 60s / early 70s did have some HD versions of the 300 six which did have forged internals, but those were only installed in very heavy service dump trucks, etc. Never into an F150.
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It's a B series Honda motor which is flat tappet. Maybe I should pop the valve cover to check valve lash.

Still, why would the noise go away with this oil?
That's not a bad idea but a lifter noise is more frequent and is a tap, tap, tap. Piston slap is sometimes mistaken as a rod knock. Hense, knock, knock, knock just not as "deep" sounding.
 
m1 0w-40 tends to shear to a 30
I’d love to see some actual third party KRL test evidence of mechanical shear, considering this is oil carries a very high number of the most stringent manufacturer-specific certifications available, and several are European standards that require “remain in grade” as part of their requirements.

Let’s make sure your data isn’t from the same crowd that thinks an oil can cure piston slap…
 
I’d love to see some actual third party KRL test evidence of mechanical shear
That would be interesting. I have zero doubt that it does considerably shear based on seeing UOAs of it for roughly 20 years, and taking fuel dilution into account. It has a large percentage of polymeric VIIs, so it is at a shear stability disadvantage. The stay-in-grade test must not be very tough to meet. I know this is blasphemy.
 
That would be interesting. I have zero doubt that it does considerably shear based on seeing UOAs of it for roughly 20 years, and taking fuel dilution into account. It has a large percentage of polymeric VIIs, so it is at a shear stability disadvantage. The stay-in-grade test must not be very tough to meet. I know this is blasphemy.
Are you sure it’s mechanical shear, or is this more probably cases of people with known fuel-diluters “going up a grade” and happening to pick M1 0w40 because it’s the best balance of cost vs certifications?

Some of HPLs oils have a decent amount of VIIs, but HPL has verified both via direct information and via UOAs that they use shear-stable viscosity index improvers. I’m pretty sure anything available to HPL is certainly available to XOM?
 
I’m sure it’s mechanical shearing. That doesn’t mean I am right, just that I am sure. I obviously haven’t presented peer reviewed data analysis and a paper, nor do I care that much about it.

I think HPL’s star polymers are quite shear stable. I don’t think I’ve seen a 0W-40 oil UOA of theirs which would really put it to the test. I think XOM and other majors are incentivized to not use highly shear stable VIIs for fuel economy reason and to not increase too much in viscosity in long engine tests.

I got to wondering about the stay-in-grade requirement. I haven’t recently read up on the details but perhaps the engine tests are very long and the struggle is not increasing in viscosity out of grade from oxidation rather than not dropping a grade from shearing. An oil that shears more would help if stay in grade if the struggle is not going up a grade. Does anybody have the test details? I know, this is a bit off-topic.
 
Just a question, since I don’t fret over every detail of Euro specs- do ANY of those specs that would cover the M1 0w40 mention fuel efficiency, though? Any VII mechanical shearing will obviously have an absolute limit of how much it possibly could shear, limiting total viscosity loss like you describe. I’m not necessarily arguing “with” you but trying to generate input…
 
It meeting MB 229.5 comes with a fuel economy improvement test (1.7%, relative to a certain 15W-40), documented on page 159, as written on the page, here: Afton document

I see a bench shear stability test on page 158. Off the top of my head, I don’t know how brutal that test is.

Some of what I’ve said in this thread is based on memories formed many years ago. Hopefully they’ve held up fairly intact and I haven’t errored too much. Haha. If I have, please point them out so I can re-learn!
 
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It meeting MB 229.5 comes with a fuel economy improvement test (1.7%, relative to a certain 15W-40), documented on page 159, as written on the page, here: Afton document

I see a bench shear stability test on page 158. Off the top of my head, I don’t know how brutal that test is.

Some of what I’ve said in this thread is based on memories formed many years ago. Hopefully they’ve held up fairly intact and I haven’t errored too much. Haha. If I have, please point them out so I can re-learn!
I would say to my uncertified eye that a less than 2% difference between a 0w40 and 15w40 oil, when all temps are considered, is a no-brainer, but maybe that’s just me. I also may not have been completely clear; I intended to mean a fuel economy gain against an otherwise same winter rating & grade oil. Ex: 0w40 of previous spec vs 0w40 of current spec. Apologies for poor communication 👍🏻
 
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