[POBEP]

I'll jump in.

My 4 data points:
- Petrol leaked through all known gaskets
- All 3 Diesels are dry

1) 2009 E91, N52K, original owner.
OFHG start leaking at ~ 58,000mi, replaced at ~90,000mi
VCG start leaking at ~90,000mi, replaced right away
OPG start leaking at ~58,000mi, replaced recently at 108,000mi
Reported OCI: 2Y/14,000mi
Engine oil changes (BMW TPT LL01):
∆, month ∆, mi mi
23 14,709 14,709
9 14,987 29,696
13 16,343 46,039
24 11,961 58,000
25 14,844 72,844
24 12,060 84,904
24 12,589 97,493
25 12,153 108,226

2) 2011 E90 M57Y, bought with 131,000mi, currently at 149,000mi
Oil: BMW TPT LL04
no oil leaks of any kind anywhere
Reported OCI: 2Y/12,000mi
Engine oil changes (BMW TPT LL04):
∆(mo) ∆(mi) mi
12 8,600 136,005
14 10635 146,640

3) 2013 E70 M57Y, original owner, 110,000mi.
no oil leaks of any kind anywhere
Reported OCI: 2Y/11,000mi
Engine oil changes (BMW TPT LL04):
∆(mo) ∆(mi) mi
7 10,694 10,699
11 10,334 21,033
12 10,805 31,838
8 7,428 39,266
9 9,664 48,930
13 10,359 59,289
11 10,696 69,985
15 9,850 79,835
15 10,160 89,995
13 10,018 100,013
11 9,987 110,000

3) 2016 F25 N47, original owner, 55,000mi
no oil leaks of any kind anywhere
Reported OCI: 1Y/8,000mi
Engine oil changes (BMW TPT LL12FE, after warranty BMW TPT LL04):
∆(mo) ∆(mi) mi
12 8,549 8,557
12 3,972 12,529
12 6,858 19,387
12 6,468 25,855
13 8,369 34,224
7 6,053 40,277
8 6,281 46,558
10 7,628 54,186

[krhodes1]

Originally Posted by Hoody007

My experience with NA BMWs is very similar to Efthreeoh - had a few 330Cis before my 335i and used the BMW CBS system. No issues with sludge. But in both cases the cars were well maintained from new.

For an N54/N55 (especially an N55 with rod bearing issues) that’s a different story - I’d do changes every 7500/10000 miles. But for an N52, provided you’re using proper BMW oil and filters, I’d go with the CBS. But this is on a well maintained car. As with any used example, it’s good practice to baseline all fluids upon purchase.

That being said I do find it interesting that the 2011+ models switched to a shorter interval-wonder if that’s to maintain parity with all of the other turbo motors used in the lineup that year.

Since they ONLY changed the OCI for North America, I have always assumed they did it to keep people from bitching about the "too long" OCI. With a side order of giving the dealers more opportunity for upsells - would you like an overpriced tire rotation, injector cleaning, and tire rotation and balance with your oil change? We HIGHLY recommend it (even though the manual says explicitly to not rotate the tires, it tracks like a TGV, and I too can dump a bottle of Techron in the tank).

These cars hold a TON of oil (for the express purpose of supporting a long OCI), and have BOTH an oil life algorithm AND an actual oil quality sensor. I have no qualms what-so-ever changing the oil in my cars when the computer sez too. But the dude changing his oil at 3K intervals like it's a '57 Chevy I thank, because I own a bunch of stock in oil companies. If he wants to light money on fire, more power to him.

[Hoody007]

Originally Posted by krhodes1

Since they ONLY changed the OCI for North America, I have always assumed they did it to keep people from bitching about the "too long" OCI. With a side order of giving the dealers more opportunity for upsells - would you like an overpriced tire rotation, injector cleaning, and tire rotation and balance with your oil change? We HIGHLY recommend it (even though the manual says explicitly to not rotate the tires, it tracks like a TGV, and I too can dump a bottle of Techron in the tank).

These cars hold a TON of oil (for the express purpose of supporting a long OCI), and have BOTH an oil life algorithm AND an actual oil quality sensor. I have no qualms what-so-ever changing the oil in my cars when the computer sez too. But the dude changing his oil at 3K intervals like it's a '57 Chevy I thank, because I own a bunch of stock in oil companies. If he wants to light money on fire, more power to him.

I especially agree on the last point. Hell even my 88 560SL, which uses regular oil, recommends an interval of 1yr/7500 mi. And that’s from the era of engineering-first at MB (so you know you can “trust” it).

[Bims328i]

Thanks for all the info an insight! I really appreciate it! Now with that said, Don't blow your gasket over a 3k oil change, in my case like I said. I noticed something like 5 oil changes on CBS (with 73k miles) after I picked up the scanner so I was doing those 3k intervals to try and clean out anything that might be in the engine I didn't know about. 7k interval seems to be the best median. I've had a lot of things start to go all of which I've replaced aside from the pan gasket and the 2nd exhaust manifold cat.

After doing the valve cover, I was pleased with the light gold coloration of the metals which is indicative of clean internals. It is not that expensive with how few miles I am driving right now. Honestly cost more for my phone bill every month than one oil change every 3k-ish miles when I do it myself.

I want to have more oil changes averaging across the miles in my car in the CBS record and for my own peace of mind. In a used car a few frequent oil changes will not hurt anything and freshen the system up without using harsh cleaners. I don't know the exact maintenance the previous owner did.

To add I do think long idling could play another role in premature seal failure. Those factors are difficult to account for as they are off odometer hours that are racked up while the car just sits and idles for an extended period for whatever reason.

It seems like perhaps the previous owner went a bit too long between maintenance periods and as a result, a number of things began to go bad due to improper upkeep. Some of it has to do with oil changes across the board. Oil is like the blood of your engine and keeping it clean will only lead to a happy motor.

My record to date
===========OIL CHANGES===========
Changed at 73350 miles 7-13-20
Changed at 76864 miles 11-1-20
Changed at 81015 miles 4-9-21
Changed at 85150 miles 8-21-21
Changed at 89966 miles 9-11-22
Changed at 92628 miles 11-20-22
Changed at 95743 miles 2-18-23
Changed at 98201 miles 5-5-23

[lookalikehuuh]

I will jump in from the sidelines and give you a heads up that I am METICULOUS about oil changes since both of my cars were brand new. I have always changed the oil at the 5K mile mark with Mobil1 0w40, even after it lost its LL01 certification from BMW. Both of my cars (225K mile 330i and 130k E50 tuned 335i) have sprung leaks like a cheap Chinese garden hose on the regular.

My 330i has gone thru a valve cover gasket every ~3-4 years. OFHG at around the same rate. Oil pan gaskets I actually saw maybe 4-5 year from each before they also sprung leaks. There is simply no stopping these engines from leaking regardless if you do 3K oil changes like you think.

For the record I used to own a Lexus IS300 with the 2JZ engine before I bought my 335i and that car NEVER sprung oil leaks during my 230K miles of ownership. Also 5K oil changes on that car with Mobil 1 advanced 5w30. My youngest brother is now the owner of that car and is still leak free as Toyota uses RTV instead of rubber gaskets like BMW.

Also your theories about fuel contamination and other issues while they might make sense in your mind don't actually hold water in real life. The reality is that unless your engine has a faulty fuel injector most fuel contamination is burnt up once the engine is up to temp as the PCV system redirects those fumes to be burned in the combustion process normally. I am also an AVID user of the blackstone labs oil analysis and they actually directly test for fuel, antifreeze, water contamination and both of my vehicles have always read below 0.5% for fuel and 0 for water and antifreeze. On a molecular level as you put it, these modern oils are specifically designed to suspend contaminants to a very high level and prevent them from affecting critical engine component.

If it gives you peace of mind by all means keep doing your 3K mile oil changes, just know that they aren't necessarily slowing down an unavoidable process of rubber hardening.

Also of note, if you use high mileage oils you might be able to potentially slow the hardening process as those oil include more seal conditioners but many german specific oil formulas are not made in high mileage formulas.

[Bims328i]

Those are really good points honestly. I'll just say unless you picked your car up new it is almost impossible to tell if you have some specific problems unless you analyze the oil.

So in my case I really don't know until I get the oil tested. From what I can gather it seems like 7k is the sweet spot from what others have said.

I did a head gasket on SC300 once and same, didn't have any real VC leaks or what have you. Those cars are pretty solid.

I'm just in the camp of disbelief that any oil can handle 10k miles of use, that seems like so many miles on one oil change to me haha.

I'm thinking perhaps the previous owner let it go over a few times. I just inspect all my seals when doing the VC and you can see this dirty nasty oil is seeping all over.

Perhaps this can be due to pushing the oil to its limits by running 10kish miles then possibly forgetting, running into maybe 15k miles.

I replaced my VC with genuine cover and gaskets at 90488 on 9-30-22 so I am monitoring the miles on it. Seems like it went along with other gaskets like OFH so replaced that too on the same day.

What parts were you using there lookalikehuuh? Are there any better options for gaskets??

If it makes you feel any better I am actually averaging an oil change every 3.5k miles.

To be honest, I think maybe needs to be a bit less like 2k haha. That oil is already dirty af at 3k.

[Efthreeoh]

Originally Posted by Bims328i

What parts were you using there lookalikehuuh? Are there any better options for gaskets??

I replaced my VCG at 305,000 miles*. I used an OE gasket with Permatex Ultra Black. 115,000 miles later (literally more miles than your has in total) and it remains leak free using 10,000 mile OCI.



*the VCG wasn't leaking. Replacement was necessary because I was replacing the ESS.

[E93Seattle (Racerbruce)]

[QUOTE=Bims328i;30187844]

To add I do think long idling could play another role in premature seal failure. Those factors are difficult to account for as they are off odometer hours that are racked up while the car just sits and idles for an extended period for whatever reason.  

please explain your rationale as to why idling could cause premature seal failure.

[CTinline-six]

If you are interested in oil chemistry, I recommend you check out the Bob is the Oil Guy forums, lots of good information there.

There are lots of variables regarding if you can use oil for 10k miles. There are plenty of used oil analysis showing it can easily hold up for 10k miles. One important factor is making sure your oil reaches operating temperature to burn off any fuel or moisture. At one point I was commuting 100 miles a day with my car, and could've easily done extended oil changes without any issue, now my commute is 7 miles, and I often work from home, so it will take years to cover the same amount of miles I was driving previously.

Seal and gasket failure is a different topic altogether. The reason BMWs leak so much is that the materials used for gaskets like the oil filter housing gasket, valve cover, etc, become hard and brittle over time from heat cycles and the higher temps these cars run at in order to be as efficient as possible. No oil will change that.

[Efthreeoh]

Shush...

No one tell the OP the N52 has ANOTHER gasket, one at mid-block that seals the part interface from the mid-block casting to the lower-block casting...

It's our little secret.

[lookalikehuuh]

Originally Posted by Bims328i

Those are really good points honestly. I'll just say unless you picked your car up new it is almost impossible to tell if you have some specific problems unless you analyze the oil.

So in my case I really don't know until I get the oil tested. From what I can gather it seems like 7k is the sweet spot from what others have said.

I did a head gasket on SC300 once and same, didn't have any real VC leaks or what have you. Those cars are pretty solid.

I'm just in the camp of disbelief that any oil can handle 10k miles of use, that seems like so many miles on one oil change to me haha.

I'm thinking perhaps the previous owner let it go over a few times. I just inspect all my seals when doing the VC and you can see this dirty nasty oil is seeping all over.

Perhaps this can be due to pushing the oil to its limits by running 10kish miles then possibly forgetting, running into maybe 15k miles.

I replaced my VC with genuine cover and gaskets at 90488 on 9-30-22 so I am monitoring the miles on it. Seems like it went along with other gaskets like OFH so replaced that too on the same day.

What parts were you using there lookalikehuuh? Are there any better options for gaskets??

If it makes you feel any better I am actually averaging an oil change every 3.5k miles.

To be honest, I think maybe needs to be a bit less like 2k haha. That oil is already dirty af at 3k.

As I stated in my post both cars have done 5K oil changes since brand new since I have owned both since they were brand new, I picked both up from the stealership myself.

Also you do realize that color of oil doesn't necessarily communicate how "dirty" the oil is right? One of the major reasons that oil turns dark is heat exposure. If you ever watch oil reviews from ProjectFarm on youtube you will see how the very first "cook" on the oil immediately darkens the oil and he is adding 0 contamination as he is heating them in a glass coffee pot. Now imagine that same oil being heated up hundreds or times or maybe even thousands of times before the oil is changed depending on how many trips you do on your car per day.

Long story short oil color doesn't mean its dirty, it just means the car has heated the oil up to temp multiple times.

The only true way to judge how "dirty" an oil or how much life the oil still has is to have an oil analysis run by a laboratory like many of us do on the regular.

I also use only genuine gaskets from FCP Euro and have had them replaced for free from FCP every time. Even my wiper blades are BMW genuine parts lol!

[CTinline-six]

Originally Posted by Efthreeoh

Shush...

No one tell the OP the N52 has ANOTHER gasket, one at mid-block that seals the part interface from the mid-block casting to the lower-block casting...

It's our little secret.

If you follow Mike Miller and change your oil every 100 miles that one won't leak.

[Efthreeoh]

Originally Posted by lookalikehuuh

As I stated in my post both cars have done 5K oil changes since brand new since I have owned both since they were brand new, I picked both up from the stealership myself.

Also you do realize that color of oil doesn't necessarily communicate how "dirty" the oil is right? One of the major reasons that oil turns dark is heat exposure. If you ever watch oil reviews from ProjectFarm on youtube you will see how the very first "cook" on the oil immediately darkens the oil and he is adding 0 contamination as he is heating them in a glass coffee pot. Now imagine that same oil being heated up hundreds or times or maybe even thousands of times before the oil is changed depending on how many trips you do on your car per day.

Long story short oil color doesn't mean its dirty, it just means the car has heated the oil up to temp multiple times.

The only true way to judge how "dirty" an oil or how much life the oil still has is to have an oil analysis run by a laboratory like many of us do on the regular.

I also use only genuine gaskets from FCP Euro and have had them replaced for free from FCP every time. Even my wiper blades are BMW genuine parts lol!

There's enough old oil in the oil pump pickup tube to discolor the oil 10 minutes after the engine is run.

This whole idea "dirty" oil leads to premature gasket failures is ridiculous. Class 8 diesel trucks have 25,000 mile OCI and 5-year 500,000-mile engine warranties. If one wants to live the Jiffy Lube lifestyle they can certainly do that, but engineers and chemists have been practicing their craft to improve their products since 1971...

[Efthreeoh]

Originally Posted by CTinline-six

If you follow Mike Miller and change your oil every 100 miles that one won't leak.

[Bims328i]

I really appreciate all the insight and personal testimony and that is truly good to hear your leak free there Efthreeoh. I suppose I'm just trying to get to
the bottom as to why I had failures on my car when I did. Seems premature to me but
I understand what you all are saying.

How is yours still leak free, any particular reason you might believe? Do you just take really good care of your car?

You're entirely right about old oil that's left in the system to tint the new oil absolutely.
And yes, you can't just determine the condition of oil simply by the color, it is only oe indicator to a degree.

In terms of long idling, E93Seattle (Racerbruce) I was reading
somewhere that idling for extended periods can be another factor in used cars. That
being it translates to you racking up a bunch of extra hours on the engine that are
obviously unaccounted for in odometer readings.

As I asked before, are there any improved gaskets for the N51/52 that you know of or
are we just doing 10k oil changes like the man says and hoping the gaskets don't go?

Any other tips you can provide to try and prolong gasket life?

[Efthreeoh]

Originally Posted by Bims328i

I really appreciate all the insight and personal testimony and that is truly good to hear your leak free there Efthreeoh. I suppose I'm just trying to get to
the bottom as to why I had failures on my car when I did. Seems premature to me but
I understand what you all are saying.

How is yours still leak free, any particular reason you might believe? Do you just take really good care of your car?

You're entirely right about old oil that's left in the system to tint the new oil absolutely.
And yes, you can't just determine the condition of oil simply by the color, it is only oe indicator to a degree.

In terms of long idling, E93Seattle (Racerbruce) I was reading
somewhere that idling for extended periods can be another factor in used cars. That
being it translates to you racking up a bunch of extra hours on the engine that are
obviously unaccounted for in odometer readings.

As I asked before, are there any improved gaskets for the N51/52 that you know of or
are we just doing 10k oil changes like the man says and hoping the gaskets don't go?

Any other tips you can provide to try and prolong gasket life?

Idling is the entire point of BMW using a CONDITION-Based Service (CBS) system. The oil life monitor accounts for load-based run time of the engine. The CBS does not just count down the oil life on mileage alone. The oil life algorithm accounts for cold starts, warm up, idle time, fuel consumption, time, miles, etc. Plus electronically measured oil contamination.

That's what everyone and me have been trying to explain to you. The oil change interval is based on the conditions the engine is used under. The system actually measures the oil contamination using the oil level sensor. The sensor is a capacitor, where the oil serves as the dielectric material in the capacitor. The sensor determines the contamination of the oil by reading its dielectric capacitance and compares that to a dielectric capacitance standard for oil contamination. It's a process developed for machine tools in the 1960s. It's not new technology, just newly applied to engine oil (20 years ago now).

You changing the oil every 3,000 miles "to catch up" on the CBS readings makes no sense. When an N52 such as mine reaches 400,000+ miles with me following the BMW CBS schedule, why does that not offer proof? 420,000 miles on 34 oil changes. A 12,300-mile average OCI. My first oil change was at +17,000 miles. I didn't get lucky, I just followed BMW's service requirements.

You then discuss used N52. Well, I have one of them too. I bought my Z4 at 8 years old and 23,000 miles. It's now at 118,300 miles, I've followed the CBS with that engine as well. Slight leak at the OFHG. The Z4 is 15 years old.

[Bims328i]

Thank you for the detailed explanation of the CBS system.
Of course you need the engine to run and idle for that system
to monitor it. I was referring to over extended idling. As in just
letting your car sit and idle for extended periods of time.

Like I said, I appreciate all of your info and expertise you provide
but I picked mine up at 73k mi and didn't get the scanner until a bit later.

I don't think the previous owner was paying much attention to
the CBS system or general maintenance for that matter.

It IS proof enough but still I did the oil changes partly to clean out
the system of anything I couldn't see and the CBS reset
was more to do with getting the number of oil changes higher
on the CBS register. I was fine with spending a bit more to do a few
frequent oil changes.

First check with the scanner, it only had something like 4 CBS resets with 73k miles. If it was accurate, that is about 18k per oil change. I wasn't entirely concerned with the availability percentage at that point but the number of oil changes within total mileage.

[E93Seattle (Racerbruce)]

you mentioned seal failures before but not in your latest post; do you believe seal failures are caused by engine idle?

[Bims328i]

Most certainly not. Maybe a potential compounding factor over time but no, not just from the engine idling.

I keep saying, prolonged idling. Not like regular idling. E.g. Like sitting in your car for 45 minutes with the AC blasting every day of summer because its hot outside. That type of thing.

[krhodes1]

Originally Posted by lookalikehuuh

I will jump in from the sidelines and give you a heads up that I am METICULOUS about oil changes since both of my cars were brand new. I have always changed the oil at the 5K mile mark with Mobil1 0w40, even after it lost its LL01 certification from BMW. Both of my cars (225K mile 330i and 130k E50 tuned 335i) have sprung leaks like a cheap Chinese garden hose on the regular.

My 330i has gone thru a valve cover gasket every ~3-4 years. OFHG at around the same rate. Oil pan gaskets I actually saw maybe 4-5 year from each before they also sprung leaks. There is simply no stopping these engines from leaking regardless if you do 3K oil changes like you think.

For the record I used to own a Lexus IS300 with the 2JZ engine before I bought my 335i and that car NEVER sprung oil leaks during my 230K miles of ownership. Also 5K oil changes on that car with Mobil 1 advanced 5w30. My youngest brother is now the owner of that car and is still leak free as Toyota uses RTV instead of rubber gaskets like BMW.

Also your theories about fuel contamination and other issues while they might make sense in your mind don't actually hold water in real life. The reality is that unless your engine has a faulty fuel injector most fuel contamination is burnt up once the engine is up to temp as the PCV system redirects those fumes to be burned in the combustion process normally. I am also an AVID user of the blackstone labs oil analysis and they actually directly test for fuel, antifreeze, water contamination and both of my vehicles have always read below 0.5% for fuel and 0 for water and antifreeze. On a molecular level as you put it, these modern oils are specifically designed to suspend contaminants to a very high level and prevent them from affecting critical engine component.

If it gives you peace of mind by all means keep doing your 3K mile oil changes, just know that they aren't necessarily slowing down an unavoidable process of rubber hardening.

Also of note, if you use high mileage oils you might be able to potentially slow the hardening process as those oil include more seal conditioners but many german specific oil formulas are not made in high mileage formulas.

Seems like a lot of gaskets unless you are doing intergalactic mileages.

My 328i and 128i are now 12 and 13 years old respectively. The 128i, which spent it's life in Austin, TX prior to my buying it 3 years ago has had all three of the usual gasket replacements, once each. Between 40 and 55K. Technically the OFHG wasn't quite leaking yet, I changed it when I had everything out for a big service anyway when I bought the car. It was basically the consistency of glass.

My 328i, which has lived it's whole life in cold Maine and barely knows what traffic is, has had no leaks at all - all three are original with no signs of issues. I will probably do the OFHG preemptively this summer, it's time to do the coolant again anyway. And that tracks with the experience of the local BMW indie I am friends with - cars in Maine tend to go a good bit farther before the gaskets leak compared to cars from down south. So presumably average underhood temps has a lot to do with it.

My 128i now lives in FL, so still in the heat. But not so much stop-and-go as it probably saw in Austin, TX, and I am in Maine for the worst of it anyway. Be interesting to see how long it goes before one of the three needs to be done again. I figure a decade anyway.

That these engines run hotter than average, and come up to temp faster than most probably helps with boiling off contaminants quickly.

[e91Owner]

This thread has become beyond ridiculous. There is no point in trying to convince the OP of anything but what he wants to believe…

[Bims328i]

Originally Posted by e91Owner

This thread has become beyond ridiculous. There is no point in trying to convince the OP of anything but what he wants to believe…

What are you talking about, it is a discussion. I think I've been quite understanding while stating such. I appreciate the helpful tips and perspective. I was trying get opinions to which there have been many along with some jokes and pokes that are not necessary. It all plays a role to some degree.