Oil filter change vs oil change

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Kent mosby

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We all know that oil will not last forever, or that an engine will not last forever without clean oil. What I cannot find is information about oil changes and oil filter changes. Yes, I have separated the 2 options.

What does the science say, not just someone's opinion? We have all been told to change the filter every time you change the oil. OK. But would the oil last longer with a filter change at say 2000 miles, ( if the recommended "oil change is 3000 miles")? Could you go 6000 miles before oil change when you change the filter every 2000 miles and still have good oil properties??

I guess you could also ask the opposite question. Can you change the oil and leave the filter?

Again, has there been any studies?

I could see using a non-bypass filter and watching the normal oil pressures. Whenever, the normal, say 75 psi, at 2500 rpms begins to drop, change the filter. Whether it is at 2000 or 4000 miles. and then change the filter at whatever interval you think is appropriate.

Finally, with many of our cars, the oil degrades by condensation and simply sitting more than use. How does that affect the oil filter and oil properties?

I guess I have too much time on my hands and I am probably thinking too hard about this. But, maybe someone has pertinent info on this.
 
This was the thinking back in 67
Screenshot_20211215-210542~2.png
 
There are additives in the oil that "wear out". There's probably a different answer depending on what oil you use and how much stuff ends up in your oil from blow by.
 
Still using conventional motor oils? Be safe, change the filter when you change the oil.
 
Ford says for regular service 7500 miles oil and filter change. Severe service 5000 miles. The Jiffy Lube and other quick change places started the 3000 mile oil change myth. .....and it is a myth. Even antiquated oils of the 60s and 70s could go much farther without worry.

That said, I don't know if there's any benefit to changing an oil filter in the middle of an oil change or not. I imagine with modern oils and additive packages, and running a good filter, it probably won't make a difference, other than the extra money spent.

Do I know for sure? No. But that's my opinion.
 
Don't know why you could contaminate new oil with old oil in the filter. Filters are not that expensive...
 
The oil filter catches particles to a certain micron. However, oil additives burn off. Oil breaks down. Oil generally degrades faster than the oil filter's filtering capabilities diminish.
Keeping your oil from getting excessively heated is the best way to ensure your oil's quality lasts for as long as possible, that means capacity. For an engine that has a large oil capacity, doesn't have cooling issues, good tolerances, proper spec and good quality oil, etc. the longer your oil will last.
I was a diesel mechanic in a previous life and our fleet trucks would get oil filter changes between oil changes along with an oil analysis. Capacity was 15 gallons so it lasts longer.
My wife and I each have Volkswagen TDi's. I would never go to this routine with one of my small diesels because capacity is just 5 liters for the little 2.0 liter 4 cylinder. The oil gets a lot dirtier in the 9,000 mi oil change intervals than a Peterbilt's 25,000 mile oil change.
For me, I would want an enormous oil capacity (maybe like a Cummins 10 gallon capacity) if I wanted to change filters between oil changes to extend the intervals. Otherwise, stick to oil and filter changes at the same time.
 
Thanks for the opinions. The biggest reason for the question was if there is any benefit to using a non bypass oil filter with filter changes more often. I understand that the PRV is there in case a filter clogs. Also, dirty oil is better than no oil. But if using a non-bypass filter and someone is not careful and a filter clogs, oil pressure drops, or does it? What I have read is that the pressure from the pump would tear apart the filter rendering it useless. AND, you would not know it.

Oil lifters are cheap compared to complete oil change, $15 vs + $45

It seems safer to run a bypass filter in a street car and change it often. I put less that 2000 miles per year on mine and I change it in the springtime, oil and filter. Wix filter and Royal Purple Duralec 10-30, a diesel oil that is also engineered for gas cars with proper zinc for my flat tappet cam.
 
i agree with Rusty.I have seen many lab tests on oil with up to 15K that is still safe to use.
Of course those companies want you to change it at 3 or 5K..it's there livelihood.
 
We are all anal (well most of us)and change oil way too often in are cars.
For me when a engine is new/rebuilt I like to replace the filter after break-in.
Then again at 500 miles.Cut them open and inspect/magnet test. Usually I go for "Months" instead of miles due to limited driving time in the Hot Rods.
 
If you guys don't reach the mileage threshold on a particular car, what time frame do you use? 12 months? 24?
 
i routinely go 3 or more years.A 1000 miles a year is a lot for most of us.
Hobbies make guys do strange things!
 
At today's $5.00 + a quart oil costs, changing the oil filter at every 2,000 miles would be a good thing. Helps separate out some of the carbons that get into the oil from combustion and any moisture that get into the filter.

As busy as everyone gets, the extra filter change at 2000 miles then full oil and filter change at 4000 miles, give you a little more of a safety barrier if you run over the recommended oil change say to 5,500 miles.

Don't think there is a downside to changing the oil filter more often as long as you fill up the new filter with fresh oil before you spin it on, then you are not starving the oil system on startup.

At the cost of vehicles now days over $30,000 dollars, would think it's a good idea to protect your engine the best you can to get the most life out of it. And keep it out of the expensive repair shops from lack of servicing at the proper intervals.

Pennzoil.png
 
My wife's car (08 Avalon) I go 5,000 miles with a synthetic blend and new filter.
My beat around cars I go 3,000 miles with new filter.I do more short trips and stop and go driving.

I have customers that go 10,000 miles and change the filter at 5,000 miles with no adverse effects on highway driving.
 
I'm just askin because we all know how stupid I am, but what would be the advantage of running a non bypass filter?

Also, playing devil's advocate kinda, why do you need a bypass filter? If your engine was built correctly and operating room CLEAN, you're not getting any dirt from THERE. Once it's broken in, you change THAT filter out for new, so it's GONE. Then, you're onto regular oil changes.

I think pretty much 100% of oil filters sold over the counter are bypass filters. I could just imagine the look on a parts store employee's face when you ask for a non bypass filter. You'd have to research it yourself, find the part number yourself and get them to order it. They'd never have it in stock, plus, they'd never know what in the world you were talking about. That's what I do now anyway. I find all my part numbers first and go in and tell them what I want.
 
I agree with Rusty.

I've always been a 5000 mile or once a year guy since the 1980's.

Now even FCA recommends "when the oil change light comes on OR not to exceed 10,000 miles".

IMO changing at 3K is throwing money (and time) away.
 
Darter6 said:
Once a year for me.
Click to expand...
I have to add sometimes the cars don't go much more than 100-200 miles in a years time.
That oil never goes to waste,lawn mowers,generators,add a quart to the old beater truck,oil door hinges.
Stuff like that.Still usable for lots of stuff that needs oilin"
 
As mentioned above, the base oil doesn’t wear out if it’s synthetic. The additive package does get consumed. How quickly it gets used depends on way too many factors to say there is any relationship between miles driven and oil change needs. The only way to know for sure in any application is to send an oil sample in at an arbitrary mileage to start with, like 3k miles and have it analyzed. Once you get the results you can see what’s left of the additive package, plus other details like fuel and coolant dilution and any bearing materiel and such. That’s the only way to know how often you should change your oil. Of course the oil that is used will also be a big factor in how often the oil needs changed. Some oils use the bare minimum additive package to make the grade.
 
oils break down. the long strands of molecules (ie the chains that make up the viscosity index) break and the VI goes down. They also absorb acids and moisture from the crankcase as well as byproducts of combustion. Sort of like your liver, your filter does its best to filter particulate but it cannot fix old thin oil. Your filters are probably cleaner that you think when you pitch them of particulates, and the color is black because of the carbon the oil picks up. Pull apart a Nissan V6 or a Stratus V6 with the PCV issue and you'll see what lack of oil conditioning/changing does to a motor...GUNK!
 
pishta said:
oils break down. the long strands of molecules (ie the chains that make up the viscosity index) break and the VI goes down. They also absorb acids and moisture from the crankcase as well as byproducts of combustion. Sort of like your liver, your filter does its best to filter particulate but it cannot fix old thin oil. Your filters are probably cleaner that you think when you pitch them of particulates, and the color is black because of the carbon the oil picks up. Pull apart a Nissan V6 or a Stratus V6 with the PCV issue and you'll see what lack of oil conditioning/changing does to a motor...GUNK!
Click to expand...


Group IV and V base oils do not break down.
 
On my newer (anything over 1990 or newer :D) daily's, I change every 5,000 miles. I'll start at, lets say, 130,***. Then I know it will be 135, 140, 145.... very easy to know when it's due. On my classics, once a year, unless it didn't get driven that year, then whenever. Cheap insurance. You got exactly what you didn't ask for, my opinion :)
 
I change the filter on my bracket car with each oil change, 25 passes & sometimes up to 40 passes, but mine is a race only application. I also cut the filter open to check the debris status, this helps to know what is wearing & if it's wearing badly. Knock on wood, I never scattered an engine or cooked the rods in one, & I'd like to think that is because I keep an eye on what is going into the filter. Just my .02.
 
I used to work for a small now extinct oil company, as a truck driver. I was some what close to the ops mgr. He told me that oil didn't break down, it was contamination. I would also go along with modifiers.
AMSOIL as I think back, started this change the oil filter and add oil thing. Seems like back in the '80's. They were one of the first commercial synthetic companies. Found out not to use synthetic grease in boat trailer wheel bearings, synthetic grease won't mix with water, regular grease does.
 
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