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Oil Change Intervals Objectively

captainbeefheart

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People speak about oil and not filter quality which is very important if you plan to go extended miles on synthetic oil.

I have always loved cars and working on them, to test my knowledge I took the ASE tests just to see how I'd do and the only one I didn't pass was the automatic transmission test but I only failed by a couple questions and I don't want to rebuild a transmission anyway but it's good to know how they work.

There are always exceptions like older designed engines in vintage cars or some exotic cars consult a professional specifically about your vehicle. With that said, your average modern OBD-II equipped passenger vehicles the average is 5,000 miles which I think is too frequent and a wast of resources and time. Get a high quality preferably synthetic element oil filter and a top quality synthetic oil and do an oil + filter change every 12 months or 10,000 miles whichever comes first. Synthetic oil still breaks down and you cold probably do two years if your cheap or 10,000 miles but from all I have read on the matter 1 year is a good time period to do the change. All cars are different and depending on how much blow by gasses you get into the crankcase and metal wear from operation are variables so to be on the safe side stick with one year. If you are the curious type and want to learn about your exact vehicle send some oil out to Blackstone labs for analysis after a year and see what they say. It's only $30 and they email the results to you in less than a week . I have had jobs with huge generators where they rushed the analysis no charge and we got results in a day of them receiving the sample.

Our 2020 G20 oil service life from the computer is between 10,000-12,000 miles depending how it's driven. They have the cartridge style filter which I like better, we typically go through the service life of the oil before 12 months is up.

As mentioned all cars consume oil, some far more than others and so although you can easily go 10,000 miles on an oil change that doesn't mean you shouldn't check it. Always check your engine oil once a month at least and top it off if needed. I do a lot of oil changes for friends and family, or if I fix a car for them most have me do an oil change while it's in for repair and the vast majority of cars are well below full. The typical 5 quart capacity passenger vehicle engine is almost always down a quart sometimes more. I have had so many cars come to me to check the MIL light due to variable valve timing codes being set from low oil, Subaru's come to mind.

Remember engine oil is not just for lubrication in modern cars, it runs the variable valve timing, timing belt/chain tension, cylinder deactivation systems etc.... so make sure you keep your oil full and clean. I've seen too many other problems besides reduced life of the engine come from poor oil maintenance, VVT solenoids clogged up is very common and sometimes you can clean the screens out. Same with the cylinder deactivation, hope it's just a clogged control solenoid because if the lifter controller in the head fails from poor oil it's going to get very expensive as the head needs to come off.

Sadly most of the people I know don't care about the maintenance of their vehicles and end up with all kinds of problems that cost them more money in the long run. I just don't get how people think all you have to do is put gas in and turn the key. As a country I truly think we need these things being taught in high school again because there are just too many adults with very poor life skills. Forget gender identity or critical race theory, that crap isn't teaching any life skills to our children, they need to learn REAL things and if they choose to educate themselves on those other matters great do so further down in paid higher education like college. High School should be more about life skills with not the intention of everyone going to college. College kids take college courses like I did in High School but I still loved shop class and other skills that have helped me through life. I also found skills and interests I didn't know I had. The education system in the USA is falling way, way behind.
 

captainbeefheart

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and most if not all modern engines have an additional spring valve in the return oil gallery that responds to oil pressure.

If you own a Nissan Titan it's probably a certain that the oil pressure relief valve is broken. Every time I see an oil cooler housing seal leak on those engines don't just do the seal, pull the body off and order the new valve. I don't know why but I hardly see any other vehicles with this problem but these they are all broken. At least the first generation. Have fun getting the old one out.

345218d1423345045-help-oil-cooler-relief-valve-1423345046199.jpg
 

RayDunzl

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As mentioned all cars consume oil, some far more than others and so although you can easily go 10,000 miles on an oil change that doesn't mean you shouldn't check it.

I agree, but my (new) 3 year old Camry has never shown any drop in level on the dipstick, with 0-16W as the recommended lubricant.

Changed at 7180, 17286, and 29781.

Looked at it a couple of days ago at 34200, and it is still as full as I filled it.

Makes me wonder what the stick sticks into.

Crazy.
 

G|force

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Beefheart- it's not uncanny that you mention a Nissan motor, to me. A long time ago I had an L24 inline 6 and I removed the valve behind the filter, tapped it to NPT thread and pluged it with a brass fitting. Long time ago! I miss that car. I ran a block heater on that engine with Valvoline w60. Isky .475 lift cam, 260 deg.
 

blueone

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What did you think? That oil filters operate at low idle oil pressure? That is correct.
No. Oil filters are designed to operate under about 99% of conditions when they're clean, the oil is the correct viscosity, and the engine is operating properly. Bypass valves exist to keep the engine from self-destructing in the case of filter failure or clogging. Like I asked before, what is your evidence that oil filters function only at "low idle oil pressure"? If you don't have evidence, I'm assuming you don't know what you're talking about.
 

Sal1950

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I have an ICE car which is driven about 2000 miles per year. Use is split between short and long trips in a warm climate. It came with synthetic blend oil but now runs full synthetic. Everything I could find says never go more than a year between oil changes without regard to mileage. However, I have been unable to find any objective data showing how much slipperiness the oil loses simply due to the passage of time. Is such objective information available or is the one-year interval something left over from the days before synthetic oil, a manufacturer's CYA or an old wives' tale?
Here's some objective data, when it starts tuning dark change it.
Synthetics are wonderful for not shearing and breaking down, but
Each engine is going to have a certain amount of blowby past the rings & valves with fuel and carbon fouling of the oil.
Don't pay attention to any oil company's claims of X amount of mileage or time.
Dirty oil is just a lapping compound that will destroy an engine in short order.
What ever you use, keep it clean.
 

mhardy6647

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This does not attempt to answer your question...
but...
Some of the late-model vehicles (Cadillac/BMW/etc.) actually notify driver when it is time to change oil.
In the old days, the notification was either based on miles driven and/or engine runtime.
[see for example, this link:]
Hondas do this as well (at least, Mrs. H's CR-V does). It feels like she's only had a handful of oil changes* in a bit over 110k miles, to date.
I haven't kept track of it, but I have a sense that it's typically 7500 miles or even more (but I may be wrong about that).
___________________
* now there's a mixed metaphor ;)
 

Blumlein 88

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Blumlein figure 8 array said:

"All espoused some version of oil not wearing out it just gets dirty, and a new filter cleans it up. That is not correct, but they believed it anyway"

May I ask if this was in the modern synthetic era or in the 70's-90's when Valvoline was the best we had?
Oh Kendall ✌️You get out what you put in. Thats true and F that crap, thanks for the direct advice Kendall. Titanium oil, cool.

Any oil filter has a bypass valve that is usually open and not filtering at all.
One could argue the reduction in oil pressure is enough to delete the filter all together and run a turn around plate if willing to do those 3k intervals.
I run a WIX filter or a oversized Motorcraft FP400, buying dozens saves money.
It was over many years. The guy with the truck is using synthetic, and is the most recent example.
 
OP
Ron Texas

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This does not attempt to answer your question...
but...
Some of the late-model vehicles (Cadillac/BMW/etc.) actually notify driver when it is time to change oil.
In the old days, the notification was either based on miles driven and/or engine runtime.
[see for example, this link:]
I had 1992 Corvette which had an oil change monitor.
 

Blumlein 88

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What did you think? That oil filters operate at low idle oil pressure? That is correct.
I think you have mistaken thinking on this. Oil bypass valves are set at low pressure like 13-18 lbs or some such. That doesn't mean they open up when oil pressure exceeds that value. They open up when the pressure differential between the two sides of the filter are at that value. With a clean filter you might well have 40-50 psi in the oiling system and only 3-5 psi pressure differential between the two sides of the filter. If its cold enough, or the filter gets dirty or maybe at very high rpm the pressure differential may go up and cause the bypass to open. If everything is working properly the bypass valve should be closed almost all the time.
 

pseudoid

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I remember that the BMWs, at one point, did away with the 'dipstick' altogether and their monitoring system kept track of oil levels.
Until some 'dipstick' neighbor was freaking out when he could not find his (car's) dipstick, with the hood open, in front of his house.
I guess he had decided that maybe he should check the oil level because his 36k warranty had run out some 11k miles ago... I had to assure him that he was due for an oil change and stop worrying about the oil levels... who was I to tell to stop being a 'disptick'?:D
That neighbor would be happy that he will never have to worry about a dipstick, in his next EV! ... Or will he?:rolleyes:
 

G|force

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Depending on the configuration of the engine, the contents of the filtered contaminates can just flow back into the pan after each shutdown, some modern engines included. (gravity)
Some low quality oil filters can blow the bypass valve out on first startup. Nobody uses a remote dual filter to be thrifty.
 

Blumlein 88

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Yeah, the Amsoil duel remote filter system. So? They are primarily for diesels that have lots of soot particles in the oil, though I guess you could use them on anything. One filter gets all the oil flow and the other gets about 10%, but filters out particles down to 1/10 th the size of the regular filters.
 

blueone

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next to last oil change on one of my cars at Valvoline used the suction method. I asked why they did that instead of draining it from the bottom but they didn't have a good reason. Last time different Valvoline drained from the plug so was happy. Don't like the idea of old oil sitting in the bottom of the pan...
The suction method usually gets at least as much oil out as a pan drain, as measured by the measured amount of oil I get out of two cars I've used both methods on. This is especially true if you use a pair of drive-on ramps to get under the car, leaving the car at an angle. With most oil pans you may be left with a pint or more from the angle. With the suction method the car stays level. Going through the dipstick also eliminates potential problems with drain bolts or stripping the threads on the oil pan. But alas, many of the latest cars don't have dipsticks.
 

captainbeefheart

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I remember that the BMWs, at one point, did away with the 'dipstick' altogether and their monitoring system kept track of oil levels.

Honestly at first I thought it was dumb but now I switched my opinion it's for the better.

Most people are not going to pop the hood and look for the dipstick let alone know enough to wipe it off then reinsert to get an accurate reading. Almost everyone knows how to use apps with a GUI so having the customer check oil level through the infotainment system is a smart move.
 

Adaboy4z

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I have a 2011 Buick Regal CXL and years after its production there was a service bulletin to change the oil sooner. So the manufacturer was wrong in the beginning. Unfortunately on the Regal forum it was too late for many. It requires synthetic and I change it very 3K because those engines burn oil. Hoping I get another 50K out of it.
 

blueone

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Honestly at first I thought it was dumb but now I switched my opinion it's for the better.

Most people are not going to pop the hood and look for the dipstick let alone know enough to wipe it off then reinsert to get an accurate reading. Almost everyone knows how to use apps with a GUI so having the customer check oil level through the infotainment system is a smart move.
I'm less convinced. For example, in our 2017 BMW oil level measurement and the oil level status display are two different functions. I suspect some owners will not read the owners manual, and will simply use the status display to check on the oil level, not realizing the level displayed may be from months before. Perhaps most other cars have better software.
 

captainbeefheart

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next to last oil change on one of my cars at Valvoline used the suction method. I asked why they did that instead of draining it from the bottom but they didn't have a good reason. Last time different Valvoline drained from the plug so was happy. Don't like the idea of old oil sitting in the bottom of the pan...

I'll tell you why. First is that cars have all different types of sealing style drain plugs like a copper crush washer, gasket style drain bolts, o-rings, etc.....Instead of having to replace these seals I'm certain it's much less of a hassle to just suck and fill instead of having the customer come back with a slight oil leak from around the drain plug, especially when you are being competitive offering very cheap oil change rates. Taking the removal of the drain plug out of the equation allows them to avoid a huge headache as they aren't liable for drain plug leakage. If a car comes to me that I need to do an oil change to and the filter doesn't come with a new crush washer or o-ring etc.. for the drain plug and or I can tell the drain plug has been leaking a little before coming to me I just clean both the pan and bolt with brake cleaner and put a dab of gasket maker silicone at the bottom threads and side of bolt head mating with the pan. I've never had one leak after that but again these places are trying to make money and cleaning everything and using silicone etc.. is time consuming not to mention the next time the plug needs to come out you have to clean all the dried up silicone off.

I think it's genius for them to go this route unless it's a high quality "lube oil Filter" service where while it's in for the oil change you look over tire pressure, windshield washer fluid, all fluids really, pump up grease fittings, grease door mechanisms and hood latch, vacuum & clean trash, etc.. In these instances doing a proper drain and making sure the drain plug is sealed correctly should be part of the service. That's how I do it, I treat all oil change services for our family cars as a complete service procedure and check everything.
 
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