If only you had someone to do your testing that is familiar with GRM.... If only.
Photography by J.G. Pasterjak
Like many components on modern BMWs, the N55 3.0-liter found in our 435i is known as a robust unit–except for its occasionally fatal flaws.
In the case of the N55, the primary boogieperson–if the internet is to be believed—is rod bearings that will destroy themselves or spin in their journals if you even give them a cross look.
Our friends at BimmerWorld feel this is an overhyped danger, but also rooted in some manner of reality. “It all comes down to service,” says Operations Manager Phil Wurz. “An engine that gets regular, or even overly aggressive fluid maintenance, is usually going to fare far better than one with improper fluid servicing. When something comes in with bottom end issues, it seems like there’s always a telltale lack of service, or gap in the records somewhere.”
So starting with a known baseline of what we were dealing with was important. As such, we changed all the fluids as soon as we got the car home, but we also sent oil samples out to Blackstone Labs for analysis.
Now, a single oil analysis is not going to give a fully rounded picture of an engine’s health, but it is going to point out any major red flags that could signal potential disaster. And once you have that initial analysis, every subsequent reports becomes that much more relevant as you can now start looking for trends and movement in the numbers.
And, we’re happy to report, that our numbers look pretty good initially.
There are no outright red flags, although there are a couple of things we’ll keep an eye on. The typical elements you see in engines with bearing or overall wear issues–iron, copper, lead, nickel, chromium, tin and aluminum–are all nice and low, hinting at low bearing and cylinder wear. The high boron reading is more indicative of the additive package in whatever the previous oil brand was rather than any wear issue.
Likewise, the other numbers trending high, like phosphorous and zinc, are also common in additive packages of premium oils.
The high sodium content can occasionally be indicative of some coolant getting into the oil, but if that’s the case, it’s usually coupled with high potassium levels and our potassium is well within spec.
Still, the oil filter housing gaskets are known problem areas on these cars, and the gaskets breaking down can allow traces of coolant into the oil system. We have a new gasket set on the shelf, though, and we’ll be doing this service at the next oil change, so by our third analysis we should know if this potential coolant issue was the case or if it was just more additives revealing themselves.
Armed with a solid oil analysis, we figured we’d test the output of our N55 under stress, so we ran it across the rollers at BimmerWorld’s dyno. And, well, if you ever needed evidence that BMW underrates their turbo engines from the factory, here you go.
Our N55 laid down 297 horsepower and 301 lb.-ft. of torque at the wheels, nearly equaling BMW’s claimed flywheel power number of 306 horsepower and bettering the claimed flywheel torque number of 295 lb.-ft. So, yeah, healthy powerplant.
Look, we’re still going to do the rod bearings at some point. We need to freshen a leaking oil pan gasket, and it’s dumb to pull off the oil pan without checking the bearings, and it’s dumb to check the bearings without just going ahead and replacing them.
But, for now at least, we’re confident that we’re not on borrowed time with our bottom end and our N55 is mechanically healthy.
If only you had someone to do your testing that is familiar with GRM.... If only.
Been doing UOAs on my car for the last 5 years - very handy tool and actually picked up an internal engine issue before a catastrophic failure. The one you have looks completely normal; moly/boron are just normal friction modifier additives. Fuel dilution looks minimal which is good based on the flashpoint but one downside to Blackstone is that they don't directly test for fuel, its inferred only so often can be a bit wonky if that's an issue you are looking at there are better labs for that.
In reply to karstgeo72 :
Their lack of testing is why I started my own private label for people like us.
bobzilla said:If only you had someone to do your testing that is familiar with GRM.... If only.
Next oil change. Let's chat.
In reply to JG Pasterjak :
Been doing UOA on my subies for a number of years. it has given me useful information - I am expecting in my next oil change on my high mileage wagon to see numbers that indicate engine is due for internal service.
Blackstone, a reliable, Very reasonable$$s, source of information.
my only use has been on Cummins engs, in motor homes. 2
think I will re account myself with my current "Fleet" 2 elderly Lexs.
thanks for the reminder.
In reply to Billbagley :
there are other options out there. Blackstone is looking at contamination only. They aren't looking at the oil itself to see the whole story because of their lack of testing capabilities. Their fuel dilution estimate is an outdated calculation based off flashpoint and doesn't actually look for the presence of fuel.
Now if you just want to see if there's contamination or likely wear and you don't care about extending oil drains or monitoring the oil condition they're fine. For my customers that are pushing their cars on track, trying to determine of the oil they are using is doing what it needs to do to protect the engine, then no they are not the best option.
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