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hey guys,

I did a bit experiment by switching to Mobile One 10W40 for warmer seasons. Here is report I got from Blackstone 7500 miles later:

We had enough oil to check for fuel this time, and there was a trace amount in the sample. That does end the string of perfect reports your M5 had going, but the good news is that a trace amount is harmless, and normally just from operational factors or sampling a cold engine. Wear metals are still in decent shape. Things have been steady for the most part aside from an increase in lead. That's worth watching out for next time, but 15ppm isn't enough to show poor bearing in this type of engine. Just check back to see how things are holding up.

One thing to note is that I added 4-5 qts of oil during this span.

I was thinking of doing the bearing job after seeing the report. Then decided to switch back to 10W60 for one more time before pulling the trigger. Here is the report after 5310 miles:

Wear metals have been been excessive for this M5, but these results are downright impressive. Check out the improvements in iron and lead, lead especially. Bearing wear was creeping up last time, but no such issues here. Maybe the bearings prefer oil runs in the 5000-6000 mile range, as opposed to 7500. Since results are so good here, you might consider sticking with this interval. There is no excesss fuel this time and the air and oil filters kept silicon and insolubles low. Very nice at 95,312 miles.

I added only 1 qt of oil this time.

The test results seem to be pointing to 10W60 as a legit viable option for our car.
 

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Shouldn't it be the reverse? You add the lower weight oil for the colder seasons. Also the fuel in the oil can be there from either i) injector issues; or ii) too many short trips where the car doesn't run at operating temperature long enough (have your driving habits changed for some reason?).

But that last 10W60 report sure seems to say it all, doesn't it? Could be either the weight of the oil, or the distance between changes, or both?
 

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Discussion Starter #3
Shouldn't it be the reverse? You add the lower weight oil for the colder seasons. Also the fuel in the oil can be there from either i) injector issues; or ii) too many short trips where the car doesn't run at operating temperature long enough (have your driving habits changed for some reason?).

But that last 10W60 report sure seems to say it all, doesn't it? Could be either the weight of the oil, or the distance between changes, or both?
Hi mate,
You are right. It should have been 'warmer'. Typo:frown

Injector is fine. Driving patterns remain pretty much the same. Both are non-factors here.
 

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I assume you meant 0w40, not 10w40?

I am about to do a 5k oil change and will be sending off the 0w40 for analysis. I have reports from PO, who used 10w60, for comparison.
 

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With thicker oil, be sure to wait when the gauge hit 150-Farenheit before running at higher RPM, and go to Red Line only when it hits 210-Farenheit. This is a standard practice for F1 racing.
 

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I use 0-40 in the winter

But through out the year as the car asks for 1L, I add 10w-60. Vanos rattle has disappeared since I started doing this. There has been a lot of talk about cavitation causing the VANOS rattle and that lower weight oils cavitate more but from using my car as an experiment I'd have to say that that theory is incorrect.

p.s. I drive less than 5000/year so I only change oil once a year. I usually add 3L of 10w-60 during the year (as needed). Blackstone tests have been stellar, except for the very 1st one ( 5 years ago ) which had high lead .
 

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But through out the year as the car asks for 1L, I add 10w-60. Vanos rattle has disappeared since I started doing this. There has been a lot of talk about cavitation causing the VANOS rattle and that lower weight oils cavitate more but from using my car as an experiment I'd have to say that that theory is incorrect.

p.s. I drive less than 5000/year so I only change oil once a year. I usually add 3L of 10w-60 during the year (as needed). Blackstone tests have been stellar, except for the very 1st one ( 5 years ago ) which had high lead .
Cavitation comes from overfill and the 'addition' of air to the oil by the pump at the surface churn (I imagine). If the oil is thicker, it will not release the air as it's being circulated as well - which will lead to the cavitation (bubble bursts = not enough oil at a critical place).
 

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i think more bubbles = less oil

Cavitation comes from overfill and the 'addition' of air to the oil by the pump at the surface churn (I imagine). If the oil is thicker, it will not release the air as it's being circulated as well - which will lead to the cavitation (bubble bursts when oil is thinner = not enough oil at a critical place).
less bubbles means less volume occupied by air thus more oil.
 

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Having certain types of bound air in the air is fine in oil, like Dissolved and Foam. The bubbles in the oil are control by additives, Temp and Pressure. Change any one of them 3 and Dissolved Air then become bubbles which do harm to the engine.
Certain additives help stop dissolved air becoming bubbles.

Oils are designed to be used in a certain engine, 10-60 in the S85 because of the design of the engine. Also look at the diff oil BMW specifies. Heavyweight stuff.

I have read on the net that M-1 causes a lot of foaming. Do a search, mainly mustang 5.0 owners.
 

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I see but the evidence says otherwise

Having certain types of bound air in the air is fine in oil, like Dissolved and Foam. The bubbles in the oil are control by additives, Temp and Pressure. Change any one of them 3 and Dissolved Air then become bubbles which do harm to the engine.
Certain additives help stop dissolved air becoming bubbles.

Oils are designed to be used in a certain engine, 10-60 in the S85 because of the design of the engine. Also look at the diff oil BMW specifies. Heavyweight stuff.

I have read on the net that M-1 causes a lot of foaming. Do a search, mainly mustang 5.0 owners.
With 10-60, My M5 got VANOS rattle unless I drove with rpm always above 3K. With M1 0-40. No VANOS rattle, regardless of rpm. The annual oil change is done around December which is very cold up here (below freezing for 3 months straight). As the car uses up oil and asks for more, I top off with 10-60 so by summer time, the car has about 7L of 0-40 and 2L 10w-60 in it.
 

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With 10-60, My M5 got VANOS rattle unless I drove with rpm always above 3K. With M1 0-40. No VANOS rattle, regardless of rpm. The annual oil change is done around December which is very cold up here (below freezing for 3 months straight). As the car uses up oil and asks for more, I top off with 10-60 so by summer time, the car has about 7L of 0-40 and 2L 10w-60 in it.
Sounds like you have other problems inside your engine if you have to use 0-40 to keep the vanos quiet.
 
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