Too frequent oil changes

[forerunner]

Originally Posted by JCL

BMW designed the filter for approximately 16000 miles (depending on your type of driving) or two years. It has safety margins built into that design. Let's conservatively say that there is a 1.5 safety factor. That means 24,000 miles as a design target. I have a hard time believing that the same engineers who designed the engine are out by a factor of 8 on the oil filter.

At the end of the day, I am with MD, do what you like, and just drive it. However, anyone who wants to use up a finite natural resource at 5 to 8 times the rate required should pay an appropriate tax, IMO. If this was fuel (which comes from the same base) then it would be equivalent to driving a car that gets 2.5-3 mpg, and considering that acceptable.

Do you have any citations on how BMW has engineered the oil filter to last this long? It still looks like a typical fibre type filtration method with the same size of previous filters so it would seem that there is still a finite amount of filtration and contaminant trapping available.

As you mentioned, the design target of 16,000 miles varies with your type of driving so this could last longer but could also be shorter.

If by paying the appropriate tax you mean the cost of materials for each oil change, absolutely. I don't think anyone expects this stuff for free.

Changing the oil every 3k would be 5x the recommended 15k interval I've seen. To get consumption of 8x would be oil changes at less than 2k miles. That's just crazy.

[JCL]

My reference for the design spec for the oil filter is the BMW service documentation, also referenced in the owner's manual. BMW warrant the engine under the standard warranty, or the extended powertrain warranty, for up to 100,000 miles, if you follow their oil change recommendations. Some will say that a plugged oil filter at 15,000 miles will not show up in resultant engine damage until after that 100,000 miles has been accumulated, but that just seems a little absurd to me.

Oil filters are not all the same. Appearance means nothing. The same factory will produce multiple filters with different media types. Those different filter media last different time spans, have different capacities, and different filtering performance (in micron rating). Absolutely, every non-purging filter has a finite capacity, agreed.

I work in km myself, not miles, but I haven't seen the oil change interval from the service indicator shorten much from the 15,000 mile base point. It seems to go longer with more highway use, but not much shorter. Of course, BMW recommend that with extreme service conditions the oil change interval should be shorter, but I am working on standard driving conditions here.

The tax I was referring to is a non-existent environmental tax that would perhaps promote conversation. Just an idea

My eight times was tongue-in-cheek, but any design engineer uses a safety factor, and I think the Germans are more conservative than some. Your 15,000 miles to failure assumes no safety margin. That's just crazy You know they have to be using something like a standard 1.5 factor just to reduce the probability of early engine failures. Changing the filter at 10,000 or 12,000 miles seems prudent. Changing it at 7,500 seems ultra-conservative. Changing it at 3,000 seems a little OTT.

Just my $0.02 Great discussion, beats many of the other standard topics here!

[forerunner]

Originally Posted by JCL

My reference for the design spec for the oil filter is the BMW service documentation, also referenced in the owner's manual. BMW warrant the engine under the standard warranty, or the extended powertrain warranty, for up to 100,000 miles, if you follow their oil change recommendations. Some will say that a plugged oil filter at 15,000 miles will not show up in resultant engine damage until after that 100,000 miles has been accumulated, but that just seems a little absurd to me.

Oil filters are not all the same. Appearance means nothing. The same factory will produce multiple filters with different media types. Those different filter media last different time spans, have different capacities, and different filtering performance (in micron rating). Absolutely, every non-purging filter has a finite capacity, agreed.

I work in km myself, not miles, but I haven't seen the oil change interval from the service indicator shorten much from the 15,000 mile base point. It seems to go longer with more highway use, but not much shorter. Of course, BMW recommend that with extreme service conditions the oil change interval should be shorter, but I am working on standard driving conditions here.

The tax I was referring to is a non-existent environmental tax that would perhaps promote conversation. Just an idea

My eight times was tongue-in-cheek, but any design engineer uses a safety factor, and I think the Germans are more conservative than some. Your 15,000 miles to failure assumes no safety margin. That's just crazy You know they have to be using something like a standard 1.5 factor just to reduce the probability of early engine failures. Changing the filter at 10,000 or 12,000 miles seems prudent. Changing it at 7,500 seems ultra-conservative. Changing it at 3,000 seems a little OTT.

Just my $0.02 Great discussion, beats many of the other standard topics here!

I was looking for more technical documentation than the BMW service documentation which can be self serving, Cynical, I know. I thought at one time I saw BMW documentation also refer to 'lifetime' fluids for transmission and/or differential. Don't quote me on that, I may have just dreamt it.

As far as accelerated wear and engine damage from improperly filtered or old oil my understanding is that this is a very slow process that could take in excess of 100k to show up which is why my reference to cheap insurance for anything I care about which isn't leased.

Re: 15k and safety margins. I'm not comfortable with them working effectively for that duty cycle and have not seen anything to have me think otherwise. I don't claim to know where the oil filter performance falls off however am fairly certain it's not within 3k.

The oil filter for one of my cars is a shared part with the E34 525. Anyone know what the oil change interval was for that car?

[JCL]

Originally Posted by forerunner

As far as accelerated wear and engine damage from improperly filtered or old oil my understanding is that this is a very slow process that could take in excess of 100k to show up ....

A filter works until it is clogged, when it goes into bypass mode. It gains some filtering efficiency as it is used. If it falls apart from age, it stops working completely. I am suggesting that that disintegration point is somewhere north of 15,000 miles, or two years, using an OEM filter.

Re: 15k and safety margins. I'm not comfortable with them working effectively for that duty cycle and have not seen anything to have me think otherwise. I don't claim to know where the oil filter performance falls off however am fairly certain it's not within 3k.

We are all entitled to our opinions. If you think that the filter will only last 20% of the published life, with no safety margin, then great (This was where I suggested an environmental tax for excessive contributors in an earlier post)

The oil filter for one of my cars is a shared part with the E34 525. Anyone know what the oil change interval was for that car?

You are referring to the oil change now, not a filter change limit. A very different oil, a different engine with many times the contaminants from combustion, and therefore a much shorter oil life. Standard practice to change the filter with the oil. If we moved from a filter change limit to a discussion of oil change intervals, we could go on for many more pages


So, as usual, MD is completely correct.

Originally Posted by motordavid

...these threads invariably get twisted and morph into
some kind of arm wrestle:

Have a great day!

[forerunner]

Originally Posted by JCL

A filter works until it is clogged, when it goes into bypass mode. It gains some filtering efficiency as it is used. If it falls apart from age, it stops working completely. I am suggesting that that disintegration point is somewhere north of 15,000 miles, or two years, using an OEM filter.

The bypassing of an oil filter is the lesser of two evils. You're recirculating dirty oil instead of suffering oil starvation. This can happen at anytime during the life of the oil filter and I'm not aware of any warning indicators for this scenario.

Originally Posted by JCL

We are all entitled to our opinions. If you think that the filter will only last 20% of the published life, with no safety margin, then great (This was where I suggested an environmental tax for excessive contributors in an earlier post)

Is that 20% of the published oil change interval or oil filter life? Does the BMW service docs speak specifically to oil filters?

Environmental tax is whole different discussion that I'm not getting into.

Originally Posted by JCL

You are referring to the oil change now, not a filter change limit. A very different oil, a different engine with many times the contaminants from combustion, and therefore a much shorter oil life. Standard practice to change the filter with the oil. If we moved from a filter change limit to a discussion of oil change intervals, we could go on for many more pages

It was a simple question. I'm not aware of any oil filter change interval that is different from the oil change interval. So I'll restate my question, does anyone know what the oil/filter change interval was for the E34 535 which uses the same oil filter as on one of my cars that has a suggested oil/filter change interval of 15k miles?

I still have yet to see exactly what has been done to the oil filter that increases service life.

[AlpineMsix]

i change my oil 4-5k.. it makes me feel better

[chefwong]

It's important to note that OCI is also based on driving style intervals - highway miles, short tripperss with alot of cold starts and engine not coming to temp, daily driver, etc.

For me, which also references based on UOA's around 7K is the limit per OCI. It's a daily driver and does get some slight fuel dilution. I change my oil whenever I swap tires - summer/winter which generally works out to be around 7/5K.

[JCL]

Forerunner:

You are recirculating dirty oil into the filter, and then filtered oil into the engine. If the filter isn't is bypass, and hasn't collapsed, then the filtered oil is meeting the cleanliness spec IMO. Your logic on the engine using dirty oil is applicable to a vehicle without a full-flow filter. Not true of modern automotive engines.

The published oil filter change interval is 15,000 miles, but it does vary with driving conditions. Yes, the BMW spec speaks to oil filters.

Not an expert here, but the E34 535 likely holds 7 quarts, was designed to use non-synthetic oil, and probably had a 7000 mile oil change interval. The filter change interval was specified because the filter held a quart of dirty oil, not because it was necessarily worn out. Some conjecture here. Those who doubled the oil change interval and ran them to 12,000 to 15,000 miles on synthetic oil would suggest that the filter is good for more than the spec mileage.

These vehicles run a lot cleaner than an E34. The best indicator of that is the tailpipe emissions. Compare the specs, and see that the engine simply isn't producing as much crap as the older models. Less to contaminate the oil. As long as you are using an OEM filter (some similar-looking filters pass larger particles than the OEM filter), you are safe with 15,000 miles on a filter. You may want to change your oil earlier, and there are reasons for doing that, but the filter isn't the limiting factor. Engineering analysis shows that, as most owners use the lights, and the lights tell them to go in at 15,000 miles. There will be a normal distribution of failure points, so it it was designed for a maximum of 15,000 miles then a portion would fail early. Hasn't happened.

If you want to do it early, that is great. I was only suggesting that taking it from 15,000 miles down to 12,000 miles would be prudent; taking it down to 7500 miles is convenient given the 15,000 mile changes that BMW pays for, and taking it down to 3,000 may just be wasteful of our earth's limited resources. Still, it is your call.

[JCL]

Originally Posted by steelgray

I seem to remember an input from someone some time ago, from some kind of a lubrication professional, that too frequent oil changes was not all that good. It was someting about the oil needing some time to do its work, i.e. cleaning and treating the metal, etc. Does someone recall this? I have searched for hours but didn't find it. It was a very thourough education in lubrication dynamics that i'd like to find again.
Greatful for any tips.

I thought that perhaps it would be good to go back to the original question, given that we have taken this topic all over the map.

steelgray:

I have read similar articles, but they are somewhat narrow in focus. There simply isn't one answer.

The makers of some of the synthetic and Moly-type products used to suggest that regular oil be used prior to using their oil, to promote proper bedding in of rings, etc. There may be a linkage to that theory.

The Society of Automotive Engineers is a pretty good source of unbiased info. A paper was presented at the 2006 World Congress on aged oil vs new oil, and how certain wear characteristics improved with the aged oil. This may be the link you are looking for. I have let my SAE membership lapse, and so can't get the full paper without paying full list for it, but here is the abstract:

http://www.sae.org/technical/papers/2006-01-1099

Jeff

[forerunner]

Originally Posted by JCL

You are recirculating dirty oil into the filter, and then filtered oil into the engine. If the filter isn't is bypass, and hasn't collapsed, then the filtered oil is meeting the cleanliness spec IMO. Your logic on the engine using dirty oil is applicable to a vehicle without a full-flow filter. Not true of modern automotive engines.

I was referring to your scenario of a clogged filter. If it wasn't bypassed, there would be oil starvation. If it is bypassed you are recirculating dirty oil. I know of no warning indicator that notifies you of a clogged/damaged oil filter. The only solution to a clogged/damaged oil filter is replacement. Shorter replacment intervals reduce the chances of this occurring and prevents you from operating in this mode for very long if it has. It's what I've said from the start, cheap insurance.

Originally Posted by JCL

Not an expert here, but the E34 535 likely holds 7 quarts, was designed to use non-synthetic oil, and probably had a 7000 mile oil change interval. The filter change interval was specified because the filter held a quart of dirty oil, not because it was necessarily worn out. Some conjecture here. Those who doubled the oil change interval and ran them to 12,000 to 15,000 miles on synthetic oil would suggest that the filter is good for more than the spec mileage.

You could very well be right but as you stated you are not an expert and this is just conjecture and suggestions. I need more than that for MY automobiles.

Originally Posted by JCL

These vehicles run a lot cleaner than an E34. The best indicator of that is the tailpipe emissions. Compare the specs, and see that the engine simply isn't producing as much crap as the older models. Less to contaminate the oil. As long as you are using an OEM filter (some similar-looking filters pass larger particles than the OEM filter), you are safe with 15,000 miles on a filter. You may want to change your oil earlier, and there are reasons for doing that, but the filter isn't the limiting factor. Engineering analysis shows that, as most owners use the lights, and the lights tell them to go in at 15,000 miles. There will be a normal distribution of failure points, so it it was designed for a maximum of 15,000 miles then a portion would fail early. Hasn't happened.

This is all well and good but needs to come from an authoritative inside source. You are conjecturing.

Originally Posted by JCL

If you want to do it early, that is great. I was only suggesting that taking it from 15,000 miles down to 12,000 miles would be prudent; taking it down to 7500 miles is convenient given the 15,000 mile changes that BMW pays for, and taking it down to 3,000 may just be wasteful of our earth's limited resources. Still, it is your call.

Egads. You've mentioned on a couple of occasions that everyone is entitled to their opinions yet look at all the real estate we wasted when I expressed mine.

I'm not going to change your mind and wouldn't if I could. But you can easily change mine. Show me what changes were made to an oil filter that was designed years earlier for some E36 and E34 models that allows it have a longer service interval for my E46. I find it absurd that the filter was overbuilt at the time and don't believe that my car runs that much cleaner now to warrant longer intervals.

Just provide documentation from a source other than BMW. BMW has a vested interest since the longer service intervals coincide with the included maintenance(in the U.S.) and BMW has little to no accountability since any failures would occur well after the warranty period, even an extended warranty period.

I enjoy working on cars(I must, I own a Ford and a rotary ) but wouldn't change the oil so frequently if I didn't feel it beneficial. I would also love to save $100+ I spend on oil and filter inserts per oil change for both my BMW's.

I'll stop now. I've doubled my total number of posts with this thread and I think we've beaten this one to death.