~6500 miles acoustics of engine change.

Posted by: BMWTurboDzl

~6500 miles acoustics of engine change. - 12/11/13 07:16 AM

Happens like clockwork. At this mileage there's a noticeable acoustic change at idle and low rpm. It goes from butter quiet to more metallic. Is this mileage at the point where a particular additive takes over/stops working?

Factory OCI is ~13k miles. Oil is Castrol OE 5w30 LL04.
Posted by: Char Baby

Re: ~6500 miles acoustics of engine change. - 12/11/13 07:31 AM

I've noticed similar sounds/harmonics toward the end of, what I call my normal OCI's(~5K miles). Smooth/quiet when the OCI is new, to some mild valve train noise(s) at the typical OCI change.

Though, I wouldn't call it noises in my engines, just more audiable!
Posted by: Phishin

Re: ~6500 miles acoustics of engine change. - 12/11/13 07:35 AM

I couldn't do it. I couldn't do 13K mile OCI's in such a nice car. Why? To save a few bucks? Not when the oil is obviously out of grade...causing your changes in engine accoustics.

Have you done any UOA's on this car?

My bet is the oil is out of grade. I bet if you drained 2 quarts out and replaced with 2 quarts of 5w40, it would sound nice and quiet again.

The noise is telling you something: the oil is out of grade (too thin). If you want to run 13k OCI's....then use a thicker oil so it will shear into grade, rather than using 5w30 and having it shear out of grade. Run a good 5w40 or even 5w50 (which are usually on the thin side of a 50 weight).
Posted by: JHZR2

Re: ~6500 miles acoustics of engine change. - 12/11/13 07:36 AM

I'd like to see a UOA to identify if it is possibly a viscosity and/or fuel related issue.
Posted by: Donald

Re: ~6500 miles acoustics of engine change. - 12/11/13 07:39 AM

I would say its more to a change in viscosity due to oxidation or shearing.
Posted by: demarpaint

Re: ~6500 miles acoustics of engine change. - 12/11/13 07:55 AM

Another vote for the oil going out of grade, and has probably been in service a little too long. Either do a UOA and see what's going on, or shorten your OCI to the point just before the acoustics change.
Posted by: BMWTurboDzl

Re: ~6500 miles acoustics of engine change. - 12/11/13 08:20 AM

Update: The factory OCI is an approximate and was for reference purposes but regarding UOA the few out there show that BMW is about spot on. It's ready to be changed for sure at 10-13k miles.

Coincidentally I was planning to change this weekend. I like the mid cycle OCI but was curious if there is a chemistry change that is neither for the better or worse with 6500 miles on the oil.

Boundary layer re-applied at this mileage?

Remember this oil is 229.51/LL04 and I'm burning ULSD.

I'm at 56k miles and haven't done anything more than a factory fill UOA. I went full OCI once.
Posted by: JR

Re: ~6500 miles acoustics of engine change. - 12/11/13 12:46 PM

Run full oci. my vw called for 7.5-10k oci's and that was in 1984 with dino oil. ran strong 6yrs ago at 380k and still going strong at over 400k.

ken
Posted by: JR

Re: ~6500 miles acoustics of engine change. - 12/11/13 12:48 PM

Diesel put soot in oil so i wouldn't think the oil is thinning out. soot loading causes oil to thicken up.

Ken
Posted by: Ducked

Re: ~6500 miles acoustics of engine change. - 12/13/13 01:36 AM

Any objective evidence for the change?

I'm not implying that a subjective assessment is necessarily wrong, just wondering if analysis of a sound recording would yield hard evidence.

Could be a whole new field of obsession. grin
Posted by: BMWTurboDzl

Re: ~6500 miles acoustics of engine change. - 12/13/13 08:30 AM

Originally Posted By: Ducked
Any objective evidence for the change?

I'm not implying that a subjective assessment is necessarily wrong, just wondering if analysis of a sound recording would yield hard evidence.

Could be a whole new field of obsession. grin


Hehe...probably would, but it would be hard for the lay person to get the variables right. It's a slight change in sound. Doesn't go from quiet to hearing valves tapping.

We hear about oils cleaning and re-applying boundary layers so I was wondering if it was at this mileage that my oil started to do it.
Posted by: outdoorsman310

Re: ~6500 miles acoustics of engine change. - 02/08/14 05:20 PM

I would change the oil. I see no reason to go that long on an oil change. oil is cheap. engines are not
Posted by: Kuato

Re: ~6500 miles acoustics of engine change. - 05/08/14 11:21 PM

Originally Posted By: JHZR2
I'd like to see a UOA to identify if it is possibly a viscosity and/or fuel related issue.


This. I'd be changing and checking it the moment the noises changed.