BMW N54 Twin Turbo

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BMW recommends using their 5W-30 oil.
I hear good things about GC 0W-30.
Does this turbocharged engine place special demands on its oil?
Any recommendations on which oil to use...
I'm thinking oil changes every 7500 miles.
 
GC is a good oil but I think 7500 miles with twin turbos may be stretching it a bit. I would go 3-4k first and get a UOA done. If all looks well then feel free to stretch it out a bit. Turbos and the heat they create can be hard on oil.
 
Change the oil with an oil that meets whatever spec BMW says it has to half as often as they tell you to.

If they say 15,000, no more than 7,500. These engines run hot and have fuel dilution issues.

German Castrol is good and meets the Longlife-01 spec the engine requires.

Mobil 1 0W-40 is another option, as are a variety of 5W-40 "Euro" oils like the Belgian Castrol 5W-40.

To meet the Longlife-01 spec it has to be a group III or better oil that can handle oxidative stress and limit coking well. With the high bulk oil temperatures (no oil cooler) I would be tempted to run a 0W-40 or 5W-40 oil in it, and limit the oil change interval to 7500 miles/1 year depending on driving conditions.

Look for ACEA A3 and BMW Longlife-01 when oil shopping. Porsche approved is another good one to look for as it has to cover some extremely high performance engines in those categories as well. GC used to be on that list but Porsche mandated no 30-weight oils.
 
The BMW oil will be good; GC might be better. Mobil 1 0w-40 is also a great option, but ehh... if BMW 5w-30 or GC works for you, there's no reason for thicker oil.

Yes, the N54 is very demanding. Two small turbos (high speeds), high oil temps, and a combination of direct injection and low friction piston rings that can increase fuel dilution. Almost every kind of thing that stresses an engine oil, all at once.

The BMW oil has moly to deal with wear; GC is most likely made with a better basestock that is more resistant to oxidation and shear.

I second the motion to do a UOA and decide on oil and OCI from there.
 
This engine is extremely tough on oil. There have been a few cases I'm aware of where BMW oil was cooked by excessively high temperatures, which caused engine failures.

Do a UOA including oxidation, and let that guide your decision on oil.
 
Heat is probably enemy #1. As I understand it, the N54 equipped 335i does not have an oil cooler (or may not have in the early models). My 535i, manufactured in Feb 2008 does have an oil cooler. I think Dinan even requires the addition of an oil cooler on engines lacking it as part of its Performance Software Upgrade packages.

Still I'm amazed just how hot the engine compartment feels in the 535i after just a short run.
 
Originally Posted By: MGregoir
These engines run hot and have fuel dilution issues.


No argument on the heat issue... But I'm curious what evidence you can show to support the fuel dilution issues.

With a direct inject fuel system, I would have thought just the opposite, since fuel requirements can be more precisely metered to the needs of the engine. And given the amazing fuel economy for the engine's power and torque, I can't imagine it having issues diluting oil with fuel.
 
If you search BMW 335i there is a 17 page thread about it.

Constant 240 to 290 degree oil temperatures and higher pressure fuel injectors than anything else just maul the oil. I am not sure how, but low tension rings and high pressure injection may mean fuel is blowing by. There is a UOA in it that shows extremely high % fuel dilution.

It's even harder on oil than the Audi FSI engines for fuel, nevermind heat.

The newer models do have an oil cooler.

RLI BioSyn 5W-40 might be able to handle it and I would almost be tempted to go hunting for Mobil 1 5W-50. This stuff destroyed ester based Motul, German Castrol, Mobil 1 0W-40, Delvac 1 5W-40...everything.
 
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Thanks for the info. Will read that thread. I hadn't taken the lower tension rings into consideration, so it makes some sense now. Guess I better plan on doing a UOA when I do my next oil change.

I still can't imagine why BMW would recommend up to 15K mile oil change intervals with this engine. Just seems wrong to me.
 
Originally Posted By: MGregoir
It's even harder on oil than the Audi FSI engines for fuel, nevermind heat.


Wow I read the thread on the development of the RLI BioSyn and its affect on the RS4 fuel dilution problem. Amazing what you learn on this site. Now you've got me runnin scared.

So should I continue to run GC till I hit 7500 Mi, do a UOA and check for fuel dilution? If perceived to be high, then perhaps switch to BioSyn 5W40? Do I thumb my nose at BMW's 4-yr maintenance (which covers oil changes using their Oil?). Difficult to decide.
 
Originally Posted By: jesbo
As I understand it, the N54 equipped 335i does not have an oil cooler (or may not have in the early models).

AFAIK, automatics without the sport package were the ones that did not have oil coolers. Someone correct me if I'm wrong.


Originally Posted By: MGregoir
I am not sure how, but low tension rings and high pressure injection may mean fuel is blowing by.

Rings that are optimized for low friction don't seal the combustion chamber quite as well, permitting blow-by; fuel gets into the oil and vice versa.

As far as how the high pressure injectors required for direct injection end up causing fuel dilution, the following is my understanding -- again, someone please correct me if I'm wrong. I think the spray just travels too quickly downward in the combustion chamber, and whatever pools around the piston rings just doesn't get burned effectively. DI engines in Europe don't have this problem because something about their fuels permits them to use stratified lean burn modes: the injector pulse is shaped so that it is locally rich around the spark plug and leaner around the edges of the combustion chamber, and the overall air/fuel ratio can be VERY lean (15.0 or more). Such lean operation could result in excess emissions with some of the fuels here in the US, which is why it is not used here, obviously to the detriment of oil life and fuel economy.
 
Originally Posted By: jesbo
So should I continue to run GC till I hit 7500 Mi, do a UOA and check for fuel dilution? If perceived to be high, then perhaps switch to BioSyn 5W40?

That would work.

Originally Posted By: jesbo
Do I thumb my nose at BMW's 4-yr maintenance (which covers oil changes using their Oil?). Difficult to decide.

Assuming you do find fuel dilution and excess wear, the next question is: how long do you intend to keep the car? If you want to run it into the ground, take their free oil changes but do your own with RLI after 3,000 miles or so, and don't tell them. If you're going to ditch the car when the warranty runs out, though, just take the free oil changes and be happy. Their warranty will cover you if you have any problems.

Of course, if your UOA comes back good, then there's no reason to worry. :)
 
Originally Posted By: d00df00d
DI engines in Europe don't have this problem because something about their fuels permits them to use stratified lean burn modes: the injector pulse is shaped so that it is locally rich around the spark plug and leaner around the edges of the combustion chamber, and the overall air/fuel ratio can be VERY lean (15.0 or more). Such lean operation could result in excess emissions with some of the fuels here in the US, which is why it is not used here, obviously to the detriment of oil life and fuel economy.


I think it has something to do with the sulphur content in the gasolines sold in NA. And that the leaner mixtures cause an increase in NO2 emissions.
 
Right! If past history is any indication, I'll keep the BMW a minimum 7-10 years. But being this is my first Bimmer, I may not tolerate the higher maintenance costs in the out years and ditch it earlier. Either way, I would care for the car the same way - I like them to last, and the next owner will appreciate that I'm sure.
 
Originally Posted By: jesbo
Right! If past history is any indication, I'll keep the BMW a minimum 7-10 years. But being this is my first Bimmer, I may not tolerate the higher maintenance costs in the out years and ditch it earlier. Either way, I would care for the car the same way - I like them to last, and the next owner will appreciate that I'm sure.


I take the same approach. Whoever buys my BMW will have one overmaintained and much loved vehicle.

For what its worth, I have had almost no maintenance costs other than the cost of fluid and filters since I bought it. I can't say the same for our 2003 Acura or any other car I've ever owned.
 
Originally Posted By: WhiteOne
BMW recommends using their 5W-30 oil.
I hear good things about GC 0W-30.
Does this turbocharged engine place special demands on its oil?
Any recommendations on which oil to use...
I'm thinking oil changes every 7500 miles.

Alittle off topic but is the TT a factory option or is that a custom setup? Any pics of your engine compartment?
 
Yeah, the 135i, 335i/xi, and 535i/xi all have twin-turbos. It's a low pressure setup with tiny turbos, more about balancing power with response and fuel economy than outright power.

Despite the technological ingenuity behind the engine, it looks just as dull in the engine bay as just about any other premium brand car engine these days...
 
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