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#1
Old 04-20-2012, 01:38 PM
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Changing engine oil but not the oil filter.

I've just ordered a new riding lawn mower and have been reading the owners manual. (No, I don't have a life.) Under the maintenance schedule, it says to change the oil for the first time after 8-10 hours of use. OK, no problem. The next oil change is after 50 hours. It then says to change the oil filter after 100 hours of use or annually. It seems weird to me that the first change doesn't involve changing the filter as well. Isn't the purpose of the first change to get out any residual crap from the manufacturing process? Shouldn't the filter be trapping that stuff? I've always been taught that when you change oil, you change the filter. Have I been misled all along?
#2
Old 04-20-2012, 01:56 PM
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I've never heard of this, and I'm with you: change the filter every time you change the oil, no exceptions.

Of course, I've never owned a lawn mower with a spin-on oil filter, but I can't imagine there is something unique to a lawnmower engine that does not require a filter change as often as an oil change.
#3
Old 04-20-2012, 02:31 PM
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My John Deere has a spin-on filter and it recommends to change the filter too.
#4
Old 04-20-2012, 02:49 PM
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Honda recommends changing the filter only on alternate oil changes for at least some of their automobiles. Our 2006 Accord and 2009 Odyssey both have maintenance schedules like that.
#5
Old 04-20-2012, 03:08 PM
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I'd change the filter. But maybe they think the larger particles that come loose in the break-in period will get stuck in the filter and not present a problem.
#6
Old 04-20-2012, 03:40 PM
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Changing filters every other change was the norm in the 60's and 70's. From the owners manual of my 1970 Chevy El Camino:

"The engine oil filter should be replaced at the first oill change and every second oil change thereafter."

Considering the minimal cost of an oil filter, however, I don't know why one wouldn't replace it at every change.
#7
Old 04-20-2012, 03:53 PM
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Isn't the purpose of the first change to get out any residual crap from the manufacturing process?

Yes.

Shouldn't the filter be trapping that stuff?

Some of it, but maybe not all of it.

I've always been taught that when you change oil, you change the filter. Have I been misled all along?

Not necessarily, but it depends on context. The concern is the filter's capacity so that it doesn't get restricted by the debris it's trapping. Presumably the engineers involved are confident that while the oil may suffer from breakdown or contamination after 50 hours, the filter can easily do its job for 100 hours. The first change (8-10 hours) may be aimed at particles too small for the filter to trap that are associated with break-in. With automobiles, the norm for decades has been what you were taught, but the counterexamples mentioned above show that it's not a universal requirement.

Last edited by Gary T; 04-20-2012 at 03:54 PM.
#8
Old 04-21-2012, 08:17 AM
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Could it possibly do any harm if I changed the filter every time? Other than to my wallet obviously.
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#9
Old 04-21-2012, 09:17 AM
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Quote:
Originally Posted by Nars Glinley View Post
Could it possibly do any harm if I changed the filter every time? Other than to my wallet obviously.
Well, there is this. Every time you change the filter there is a chance of a few things happening. One, you get a defective filter, which will be bad. Or the new filter isn't installed properly and leaks (bad) or strips the part on the engine it screws onto (also bad).

So, one could argue that changing the filter more often than needed leads to unneccesary risks.

Though, personally I am old school and would take those very minor risks anyway. And for me, its not getting rid of that old nasty oil that is in the filter that bothers me almost as much as not changing the filter itself. I like my oil in the engine to start off very clean at the beginning of a change so I can track the color changing better as it gets old.
#10
Old 04-21-2012, 10:00 AM
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Quote:
Originally Posted by billfish678 View Post
Well, there is this. Every time you change the filter there is a chance of a few things happening. One, you get a defective filter, which will be bad. Or the new filter isn't installed properly and leaks (bad) or strips the part on the engine it screws onto (also bad).

So, one could argue that changing the filter more often than needed leads to unneccesary risks.

Though, personally I am old school and would take those very minor risks anyway. And for me, its not getting rid of that old nasty oil that is in the filter that bothers me almost as much as not changing the filter itself. I like my oil in the engine to start off very clean at the beginning of a change so I can track the color changing better as it gets old.
Interesting considerations. But I'd also change the filter. It doesn't seem like those risks are as great as the damage to engines of dirty oil. Except maybe that's all in my mind. I do like to see the oil looking clean to start with. I suppose most of the color change is due to harmless combustion product, but I'm not doing a microscopic analysis of the oil to tell what's made it dirty either. Seeing the oil turn black seems like the best way to determine it needs changing. And there always the chance that the filter you have will fail and start letting large particles pass through. So the risks run either way.

Last edited by TriPolar; 04-21-2012 at 10:02 AM.
#11
Old 04-21-2012, 10:09 AM
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Improvements in manufacturing and casting practices have pretty much eliminated the residual contaminates from a modern engine. That said, oil filters are rather cheap and easy to change, so I can't imagine not changing one with the oil.
#12
Old 04-21-2012, 10:17 AM
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Quote:
Originally Posted by Morgenstern View Post
Improvements in manufacturing and casting practices have pretty much eliminated the residual contaminates from a modern engine. That said, oil filters are rather cheap and easy to change, so I can't imagine not changing one with the oil.
right, but there's still a bit of residual metallic bits as e.g. the piston rings seat into the cylinder walls. Though as you said, improvements in manufacturing have made it so that at least car manufacturers rarely bother to specify a break-in interval. Back in the day it was "conventional wisdom" that you changed the oil on a new car before 1,000 miles, and normal intervals afterward.
#13
Old 04-22-2012, 07:11 PM
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Back in the 60's and 70's, as mentioned, many cars had the "every other oil change" schedule. They also had a 6K mile recommendation for oil change intervals.

Amazing if you think about it... you could have a filter on your car for 12K miles, and this was the recommendation of the manufacturer.

I believe that the 3000 mile oil change is one of the great marketing successes of the late 20th century. Oil companies were able to convince just about everyone to change their oil on a 3000 mile cycle instead of the 6K schedule, and basically doubled their consumer oil sales.

Do I follow that schedule? Yes, mainly because like most people, it seems like a reasonable cost for ensuring my engine is running clean oil. But does it need it? I doubt it. (I change the filter, too).

A friend of my father's NEVER changed his oil. He would change his filter and add a quart or so of oil every 5K miles, and never had any problems. It sounds like it could possibly work, as you are putting a new quart of oil in with the old, and have a new filter to catch any impurities.

I'd never do it.

he did this with cadillacs, so he was rolling the dice on expensive engines. And according to his sons, my father, and anyone else I spoke to, he was actually doing this. I guess he could have been making it up, but I have no reason to think so.

I would never buy a used car from the guy, though,

Last edited by crypto; 04-22-2012 at 07:12 PM.
#14
Old 04-22-2012, 07:35 PM
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Being a gearhead and former drag racer, I tend to go overboard with maintenance. Better than the other extreme, I guess. Anyway, I used to be on the 3K/oil & filter interval with our cars. Then, after considering how and where we drive, I now change every 5K. And while synthetic oil is superior, I do not use it. Should I ever opt to extend the intervals to maybe 8K-10K miles, I would go with synthetic.
#15
Old 04-23-2012, 11:50 AM
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Everyone here seems to be talking about car engines, but the OP is about lawn tractor engines. I don't know if that makes a lot of difference, but just trying to get the thread back on track.
#16
Old 04-23-2012, 03:42 PM
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The company I work for specfies changing the filter at every other oil change due to engine wear issues. This applies to both the automotive/truck and power equipment engines... tractors, generators, etc.

A new filter takes several seconds to fill with oil when the engine is started, which causes a prolonged zero oil pressure condition with the engine running.

BTW, only a fraction of the engine oil passes through the filtration media during normal engine operation. A lot of people are under the impression that the bypass valve in the filter is either "open" or "closed," meaning either all the oil is passing through the filter, or none is. In reality, about 10-20% of the oil pumped through the filter makes it through the media, and the rest passes unfiltered.

This is acceptable because engines don't tend to clutter up the oil very quickly; the filter is more of a safety device against incidental large particles than it is intended to capture small wear particles.
#17
Old 04-23-2012, 04:02 PM
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Quote:
Originally Posted by Kimballkid View Post
Everyone here seems to be talking about car engines, but the OP is about lawn tractor engines. I don't know if that makes a lot of difference, but just trying to get the thread back on track.
I'd say the basics are the same.
#18
Old 04-23-2012, 04:13 PM
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Quote:
Originally Posted by blasto9000 View Post
The company I work for specfies changing the filter at every other oil change due to engine wear issues. This applies to both the automotive/truck and power equipment engines... tractors, generators, etc.

A new filter takes several seconds to fill with oil when the engine is started, which causes a prolonged zero oil pressure condition with the engine running.

BTW, only a fraction of the engine oil passes through the filtration media during normal engine operation. A lot of people are under the impression that the bypass valve in the filter is either "open" or "closed," meaning either all the oil is passing through the filter, or none is. In reality, about 10-20% of the oil pumped through the filter makes it through the media, and the rest passes unfiltered.

This is acceptable because engines don't tend to clutter up the oil very quickly; the filter is more of a safety device against incidental large particles than it is intended to capture small wear particles.
I'm not disagreeing but I've never heard of this. This implies that all oil going to the working parts of the engine goes through the filter first. Is that how it really works?
#19
Old 04-23-2012, 05:21 PM
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Quote:
Originally Posted by Stink Fish Pot View Post
Back in the 60's and 70's, as mentioned, many cars had the "every other oil change" schedule. They also had a 6K mile recommendation for oil change intervals.

Amazing if you think about it... you could have a filter on your car for 12K miles, and this was the recommendation of the manufacturer.

I believe that the 3000 mile oil change is one of the great marketing successes of the late 20th century. Oil companies were able to convince just about everyone to change their oil on a 3000 mile cycle instead of the 6K schedule, and basically doubled their consumer oil sales.

Do I follow that schedule? Yes, mainly because like most people, it seems like a reasonable cost for ensuring my engine is running clean oil. But does it need it? I doubt it. (I change the filter, too).

A friend of my father's NEVER changed his oil. He would change his filter and add a quart or so of oil every 5K miles, and never had any problems. It sounds like it could possibly work, as you are putting a new quart of oil in with the old, and have a new filter to catch any impurities.

I'd never do it.

he did this with cadillacs, so he was rolling the dice on expensive engines. And according to his sons, my father, and anyone else I spoke to, he was actually doing this. I guess he could have been making it up, but I have no reason to think so.

I would never buy a used car from the guy, though,
Just as an aside, I have second beater car to my Mustang that I drive (a 2001 Hyundai 300XG) in bad weather and for general commuting to work and it burns a decent amount of oil (140,000 miles, 11 years old) and I think that since I need to add a quart about every 1,000 miles that I can go longer in between oil changes (about 5k instead of 3k). Am I wrong to assume this? The filter gets changed every time the oil does.
#20
Old 04-24-2012, 11:41 AM
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Oil thread!

Follow the manufacturer's recommendation.

Cheap oil filters manufactured to crappy standards work well over time and worse when new. This is true of even semi-decent filters. They can be found on utility equipment. They are inferior to filters found on better equipment.

New filters are worse than slightly used filters in some applications.

.

Last edited by Philster; 04-24-2012 at 11:43 AM.
#21
Old 04-24-2012, 04:33 PM
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Quote:
Originally Posted by Nars Glinley View Post
I'm not disagreeing but I've never heard of this. This implies that all oil going to the working parts of the engine goes through the filter first. Is that how it really works?
Going through the filter "first" depends on how you look at things. Modern engines put the filter close to the output of the oil pump, so if you consider the oil pan/reservoir to be chronologically first, then the oil goes through the pump, then the filter, then to the main bearings and rest of the engine.

On some engines, the oil filter is installed with the open end up. Gravity is relied on to help keep particles trapped in the filter, and does a surprisingly good job at it!
#22
Old 04-24-2012, 04:55 PM
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Quote:
Originally Posted by blasto9000 View Post
Going through the filter "first" depends on how you look at things. Modern engines put the filter close to the output of the oil pump, so if you consider the oil pan/reservoir to be chronologically first, then the oil goes through the pump, then the filter, then to the main bearings and rest of the engine.

On some engines, the oil filter is installed with the open end up. Gravity is relied on to help keep particles trapped in the filter, and does a surprisingly good job at it!
Would filling the filter up with oil before installing it do any good? Assuming of course that the amount added to the filter was subtracted from the total oil volume.
#23
Old 04-25-2012, 09:57 AM
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Quote:
Originally Posted by Nars Glinley View Post
Would filling the filter up with oil before installing it do any good? Assuming of course that the amount added to the filter was subtracted from the total oil volume.
I'm a business analyst, not an engineer, so I had to ask an engineer about it this morning. This thought has crossed my mind before but I never thought to ask.

So the engineer's reply was that fresh oil from the bottle typically has some contamination in it already, and filling the filter would give any grit in there a "free ride" to the main bearings. So, pre-filling the filter is not a recommended practice.
#24
Old 04-25-2012, 11:14 AM
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Quote:
Originally Posted by blasto9000 View Post
I'm a business analyst, not an engineer, so I had to ask an engineer about it this morning. This thought has crossed my mind before but I never thought to ask.

So the engineer's reply was that fresh oil from the bottle typically has some contamination in it already, and filling the filter would give any grit in there a "free ride" to the main bearings. So, pre-filling the filter is not a recommended practice.
That's interesting. It seems that pouring oil directly into the top of the engine would have that effect as well.
#25
Old 04-25-2012, 11:18 AM
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I usually pre-fill the oil filter when I change the oil on my cars. I doubt it has any real affect on the longevity of the engine, but it does seem to shorten the length of the sickening moment when you first start the engine after an oil change and the oil light stays on.
#26
Old 04-25-2012, 01:09 PM
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Quote:
Originally Posted by Nars Glinley View Post
It seems that pouring oil directly into the top of the engine would have that effect as well.
No, that oil drains into the crankcase where it is sucked into the oil pump then pumped into the filter and then on to the main bearings. Apparently the oil poured into the filter before installation is at the outlet side of the filter and thus does not get filtered at first.
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