Rod Bearing Break-in (hint: there isn't a need)

[Tjkenny15]

Seems silly not to break in rod bearings, for any car, even if it isn't 100% necessary. You just spent a lot of time and money to get your s54 healthy again, seems foolish not to.

I break in literally everything, electronics, rotors, pads, my car battery, shoes... its peace of mind at the end of the day.

[Tbonem3]

Poor logic.

If it doesn't need it, it doesn't need it.

Should we do a break in after valve adjustments too???

[tnord]

maybe not valve adjustments, but we should break in water pumps and alternators, they have bearings too you know!

[jbfrancis3]

Maybe I should've broken in my new tube of toothpaste

[Syfon]

Rod bearings don't require break-in.

If you're motor is brand new or freshly built, different story altogether.

If you've just replaced rod-bearings as a course of routine maintenance, breaking them in is a waste of time. Always wait for oil to reach temp, then send it. Per usual.

[lemoose]

It shouldnt need it- but people in this thread are basing that off the fact that they are supposed to be a contactless surface which is comical because we all know empirically hasnt been the case for this motor- hence why were all here discussing bearing jobs.

unless youre taking the rods out and checking clearances and round with a micrometer- truth is you really dont know if there will be contact. Im willing to bet that 90% of s54 rod bearing jobs dont go to such length. Best case scenario they probably plastigauge it and call it a day. So at least for these jobs, A “break-in” procedure could save you from one of the more catastrophic failure modes for bearing contact.

in any case I dont believe a break in is necessary but thats just because i think the s54 bearing issue stems from a combination of 3 things:
- tight tolerances that made proper oil temp imparative
- accessible price point which led to many novice owners who didnt appreciate the above
- large production numbers for such a high strung motor which amplifies the perceived failure rate

[Chanman1029]

What sort of break in oil do you recommend? I just did a full rebuild, and was recommended to use 15w-50 break in oil by driven, does that sound right?

[Tbonem3]

Using a less viscous (when cold) oil doesn't make sense. Just use your regular oil IMO. If in a cold climate, if you're worried, run some euro formula 0-40 or usual bmw spec 5w30.

It's not about possibly making contact or not, it's about seating - making contact on purpose.

Piston rings must take a set in a freshly diamond honed cylinder for maximum compression. The rings scrape the "peaks" created by the honing, to make a flat surface.

You're not preparing the crank to mate with new bearings such that a break in would create a new relationship between the two surfaces. You're not modifying the surface of the crank such that the new bearings will "seat" against it like a cylinder wall.

[jet_dogg]

So which oil?

[eljay]

So which oil?

Standard M spec 10w60 oil. Let's not have an oil discussion thread here.

Some people also just use oil to lubricate every surface prior to bearing assembly and some use an engine assembly lube. From what I've read, both methods work fine.

[Chanman1029]

Standard M spec 10w60 oil. Let's not have an oil discussion thread here.

Some people also just use oil to lubricate every surface prior to bearing assembly and some use an engine assembly lube. From what I've read, both methods work fine.

its break in oil, in a break in thread, seems pretty relevant to me….

[Tbonem3]

The BMW break in procedure is about rpms for a particular period (miles), not oil.

[Jimbo's M]

Easy to just to forget what the dealer said except for one tiny detail in my case, I was still under full warranty even after the second bearing change. Doesn't matter what I think, and trust me, doing it their way three times was brutal. So, the way I see it is either you do their way or face something effin' up that I would be liable for because the DME or whatever fibbed on me. If you guys are so smart about bearings, why don't you give BMW M engineers a ring and tell them they're full of shit. I'll watch.

[Chanman1029]

The BMW break in procedure is about rpms for a particular period (miles), not oil.

Genuine question, is changing the oil not part of the procedure?

[old///MFanatic]

Genuine question, is changing the oil not part of the procedure?

Nope BMW states directly in regards to the Rod Bearing Campaign, “Engine oil service is not required after completion of engine break in period”. I posted this document section in post #52.
There is also no code given to pay for a 1,200 mile oil change after this procedure. Nor did we get a notice for one. We did get a full tank of gas, car washed and valet service even covered by BMW. BMW dealerships were given all those codes for reimbursement.

New ENGINES are different. Yes oil change service ~1,200 miles.