[AU-bmw335i]

I'm paranoid about bearing failure due to leaking injectors but don't don't a spare $1300 to throw at new injectors. So I decided to do a used oil analysis. See result below.

Unfortunately the analysis I choose doesn't tell me the level, only whether or not fuel dilution is above 3% (which it is)

Car is 08 e90 335i with 75,000 km (50k miles) on it. Mhd stage 2 tune with Fmic and downpipes if that matters.







Should I be concerned? Anyone else done a similar oil analysis

[JuniorB]

Absolutely, any fuel will dilute and break down you oil. Check plugs for indication of unburned fuel, and misfires. What index are you running,? You definitely want to fix this asap.

[MysticRob]

Why not just check for signs of which injectors, coils, or plugs are not working correctly and replace those specific offenders? You're also quoting prices about 50% above the actual cost if you check various parts sources and threads here.

[AU-bmw335i]

Originally Posted by JuniorB

Absolutely, any fuel will dilute and break down you oil. Check plugs for indication of unburned fuel, and misfires. What index are you running,? You definitely want to fix this asap.

Current index is 9 with one 6 for some reason. No misfires and AFR and fuel pressure looks good in logs.

Originally Posted by MysticRob

Why not just check for signs of which injectors, coils, or plugs are not working correctly and replace those specific offenders? You're also quoting prices about 50% above the actual cost if you check various parts sources and threads here.

I haven't checked plugs, but yes I will do that. I replaced plugs and coils 3 months ago, so I know they are good.

Not sure where I can buy injectors for the price you are suggesting. FCPeuro has them for $214 each which is $1300 for 6 once you include postage (Im not in the US). Can get some genuine for maybe $50 cheaper on ebay, but not 50% cheaper.....

[hellokitty]

Look for used injectors.

[feuer]

@AU-bmw335i lead and tin is OK, nothing alarming. Is your engine idling a lot?

[JuniorB]

Looks like a low mileage car, does it sit a lot, if it does, clean and reinstall your plug and inspect them for gas. A good indication of a leaking injector. Also so a sample a 3k, see what comes up. Is this the first time you’ve done OSA, anything before?

[AU-bmw335i]

Ive only had car about 6 months. I have done a lot of maintenance on it, plug, coils, VCG, OFHG, O2s, trans service ext. I drive it most days, but my commute is only 20-30 minutes around town, no freeway.

Previous owners didn't drive it much I guess. It has been regularly serviced at BMW until recently. This is the first oil analysis I have done.

Interesting Video on oil dilution.

So the question seems to be is the "Minor fuel dilution" in my oil analysis normal, or more serious as in a leaking injector. Guess I will take the plugs out and have a look.

[MysticRob]

Originally Posted by AU-bmw335i

Current index is 9 with one 6 for some reason. No misfires and AFR and fuel pressure looks good in logs.



I haven't checked plugs, but yes I will do that. I replaced plugs and coils 3 months ago, so I know they are good.

Not sure where I can buy injectors for the price you are suggesting. FCPeuro has them for $214 each which is $1300 for 6 once you include postage (Im not in the US). Can get some genuine for maybe $50 cheaper on ebay, but not 50% cheaper.....

There's a thread floating around, I thought here, or on another forum that O'Reilly's, AutoZone, etc, have new Index 12s for $1xx.xx pricing. Search the interwebs and do some coupon deals to get the price as low as you can.

Typically I'll find the lowest price I can, then give that to the dealership parts guy, and let him either match or come close so I don't need to wait on shipping from someone else.

[AU-bmw335i]

Thanks. I am in Australia which makes it difficult with shipping. I went with FCPeuro. US$204 each with last chance discount.

[JohnDaviz]

I am on the same boat

I spun rod bearing (really bad) on 60k mile N54. 2k miles before that i changed to index 12 injectors because of cold start rough idle and codes.

Changing bearings costs way less money than engine rebuilt! If you are paranoid.

1. Change to index 12
2. Check oil filter for particles
3. Change rod bearings anyway

In the end 1. + 3. will be cheaper than a rebuilt or used engine.


Forgot one point from your oil analysis.

What do you think the copper is coming from?

Just my 2 cents with a killed well maintained engine...

[AU-bmw335i]

Thanks for the advice. At this point I think I will replace injectors and continue to monitor with oil analysis. Oil analysis is pretty easy and cheap.

In regards the readings, the elements all look OK. The report comes with a sheet of acceptable max values (e.g. Copper is 22) and all values are below.

Silly/obvious question - what material are the bearings made of on the N54? I have searched but can't find this info.

[JohnDaviz]

Bearings are made of multiple layers.

N54 rod bearings are tri-metal bearings:

http://kingbearings.com/files/Engine..._Materials.pdf

I am not sure if our camshaft bearings do have a copper content, but according to Mahle data sheet of their bearing materials, most likely ours will have copper content.

But for sure the first layer of your crankshaft bearings is copper followed by a second layer.

[AU-bmw335i]

Originally Posted by JohnDaviz

Bearings are made of multiple layers.

N54 rod bearings are tri-metal bearings:

http://kingbearings.com/files/Engine..._Materials.pdf

I am not sure if our camshaft bearings do have a copper content, but according to Mahle data sheet of their bearing materials, most likely ours will have copper content.

But for sure the first layer of your crankshaft bearings is copper followed by a second layer.

Great info. Thanks.