Mobil 1 0W-40 might be cleaning my VW 1.8T engine

[JAG]

Over the last 15k to 20k miles, it has had brown varnish stains in the valve cover area from some previous oils and/or oil additives. I don't know what the offenders were but over this time I used Lubromoly 5W-40, 0W-40, MoS2 additive, Auto-RX...NOT all used at once. I used these products for several 5k to 6k mile OCIs. Engine has 80k miles on it now.

I used to use Mobil 1 0W-40 oil (API SL version) early in the engines life and the engine surfaces always looked like new on it with 5k mile OCIs. I went back to this oil 3.5k miles ago (API SM version), drained it at 3.5k miles because it got quite dark looking and seemed to loosen small debris that I saw sitting on engine parts. I filled up with it again. Currently a hundred miles into this interval. The stains inside the valve cover seem to be lessening. If I had taken pictures I could say for sure but didn't. But by memory, it appears to be so. I'll see how it goes from here. This is not proof, of course. That's why I said it "might be cleaning".

I should use solvent to clean off a strip of the valve cover metal and take a picture. It will show the varnish darkness and the clean metal color. Then when I fill up with next oil change (same nearly clean looking oil in engine), take another picture. Then I would have proof or be able to disprove it.
It's probably premature for me to even make this thread but it's partly me just making notes for future reference for myself.

 

[wavinwayne]

That M1 0w40 is "shearing" the deposits right off.

I've used the SL version many times in my VW 1.8T, too. It always kept the engine clean-looking, but I'm not sure if it did any additional cleaning. I think it just did a good job of preventing future deposits from forming.

 

[JAG]

Quote:

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That M1 0w40 is "shearing" the deposits right off.

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BTW, when you look inside the valve cover at the back wall in your 1.8T, how would you describe the color? Perfectly clean metal, slight brown, ...? And how many miles do you have?

 

[wavinwayne]

The valve cover on mine is dark, dark brown with varnish stains, but the top end of the engine, that actually sees oil flow to some degree, is still shiny clean.

 

[Lonnie]

With M1 0w-40 have you ever done a uoa to see if the 40 weight sheers down?

 

[JAG]

Thanks Wayne. That's what I'd expect since you ran dino for a while and I never have. Your valve cover is dark brown and mine is now very light brown. I would have had my hands in the air if you said yours was squeaky clean everywhere!

Lonnie, yeah M1 0W-40 definitely shears in engines that put a whompin' on oils. That's just how it goes with 0W-40 oils because they require a good amount of polymeric thickeners. Their viscosity indeces can be around 190. They still maintain pretty high HTHS viscosity after shearing which is what matters most once the engine is warmed up. Based on kinematic vs HTHS viscosity relationships, I think that the HTHS of M1 0W-40 very rarely drops below 3.3 cP, which is 10% higher than the 3.0 typical of most 30 weight synthetics. Of course, some very shear stable 30 weights meeting ACEA A3 like GC start with 3.5 or 3.6 cP and probably keep it the whole interval. I got better gas mileage with M1 0W-40 than GC, probably partly because of that.

 

[wavinwayne]

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With M1 0w-40 have you ever done a uoa to see if the 40 weight sheers down?

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I have. There are two of mine buried in the UOA archives. Both times, M1 0w40 sheared to a 30wt, even with mostly easy highway miles. It protected the engine just fine, though.

 

[StoicDude]

Interesting. Are the the longitudinal mounted 1.8Ts or the transverse?

Mine is a transverse AWP and I just checked under my oil filler cap. The top, which is what you are most likely referring to, is slight brown in the back (facing the cabin) while the front is a bit darker.

Like wavinwayne said, the area underneath it, which is the top end of the engine is clean. No deposit or brown stuff at all.

I am using GC, but have used M1 before and the numbers with GC were better. Iron was better and GC ended up being thicker than M1 during the same interval and driving.

I ran dino for the first 20K with 3K OCIs (pre BITOG days. Ohh I saw the light and my pocket keeps on getting lighter).

 

[StoicDude]

Just a side observation; Is that 1.8T cam made out of plastic or what? It looks like it is. I didnt touch it but certainly seems like black plastic.

 

[moribundman]

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Just a side observation; Is that 1.8T cam made out of plastic or what? It looks like it is. I didnt touch it but certainly seems like black plastic.

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Biggest guffaw of the week!

 

[StoicDude]

Biggest guffaw of the week!

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I guess I might be wrong, but I will take a pic and post it.

 

[JAG]

StoicDude, the cam is covered in a black plastic shroud. No need for you to take a picture of it!

Wayne and I have transverse 1.8Ts. Mine's an '03.

Yes the area I was talking about is at the top back (facing the cabin) when you look into the oil fill cap. It's a smooth piece of metal about 1.5 inches in height...under it is a black seal and I presume the cylinder head.

The reason I switched long ago from M1 0W-40 was the iron levels in UOAs compared to GC, Valvoline 5W-40, etc. But the great gas mileage, strong TBN, and cleanliness of M1 0W-40 has got me back on it for now at least.

 

[TTopJohn]

If GC ever becomes unavailable, I think I'll go with M1 0w40. Shearing down is not a concern for me, as I figure since M1 0w40 starts out thicker than GC anyway, it's got some room to shear. I don't need a true 40 weight, a thickish 30 weight (basically, something about the weight of GC) is fine for my needs. OTOH, the 740 could take 5w40 Castrol Syntech too, but that might be a touch thick for the Camaro, and I like only having to stock one oil.

 

[buster]

M1 0w-40 is a good oil. You can talk about factory (buy in) all you want, the oil still meets a lot of specs and is found in many high end cars.

 

[Turbodriven]

Im happy with the Mobil1 0-40, my 2.0 OPEL turbo motor runs very well on it. My current fill has 3000km on it and its still that golden brown colour and it has not used a drop.
I will change it out at 7500km and take a sample.

I would like to have tried Motul's products, but sadly the agent bringing it into SA appears to be very uninterested in getting the product to customers....it arrived in January at customs and it's still there!!

 

[Syntec-Man]

my friend has a jetta he puts some werid oil in there Jack Lem 5w40? never heard of jack Lem

 

[paul_e320]

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.......I think that the HTHS of M1 0W-40 very rarely drops below 3.3 cP, which is 10% higher than the 3.0 typical of most 30 weight synthetics. Of course, some very shear stable 30 weights meeting ACEA A3 like GC start with 3.5 or 3.6 cP and probably keep it the whole interval. I got better gas mileage with M1 0W-40 than GC, probably partly because of that.

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JAG,

Inquiry from a novice: How can M1 claim they meet ACEA A3/B3/B4 when that oil drops below the "> 3.5 cP" requirement? I don't see any time parameter on the ACEA sequence and I'm not familiar with CEC-L-36-A-90.

Regards,
paul...

 

[JAG]

That HTHS requirement in ACEA A3/B3/B4 is for virgin oil only. Kinematic viscosity stability is measured in one of two tests (CEC-L-14-A-93 or ASTM 6278; both run for 30 cycles), which are of course different than the HTHS test. The oil passes those tests. How it behaves in different engines is another matter. In some engines, it barely shears, while in others (like in my engine), it can shear to the level often described of it. But the VIIs are what shears and causes the loss in kinematic viscosity but they don't add to the HTHS as much as they do to the KV. HTHS loss % has been found to be about half the % loss in KV. Basically, this oil's engine protection, viscosity-wise (HTHS) is that of either a thick 30 weight or a thin 40 weight, depending on how much the engine shears oils and how long it's been in use.

 

[paul_e320]

JAG,

Thanks for the info. As usual, you've provided me with great explanations that help me, a layman, to learn and understand more about the oil in my car(s).

Regards,
paul...

 

[TeeDub]

JAG,

I've spent a lot of time thinking about this 0w-40 shearing stuff and the HT/HS viscosity test...here are my thoughts.

In the HT/HS rate test, the polymeric thickeners align themselves in the direction of flow, so they don't really provide that much benefit in terms of viscosity. This is why an SAE 0w-40 with a kinematic viscosity > 14.0 Cst @ 100C only has a HT/HS of approx 3.6 Cp @ 100C. By contrast, in the low shear rate, kinematic viscosity test done @ 100C, these polymers work as advertised an enable you to achieve specific SAE grades.

So it makes sense that thinning in terms of kinematic viscosity does not directly translate into the same # of viscosity loss in the HT/HS test.

Does that make sense???

TS