Duration with Synthetic oil

[jcniest5]

If this has already been posted somewhere, would someone plz point me to it. My question is how often do I change my oil when it is synthetic oil? Someone said every 10K miles, others have said every 6K miles, which is correct? TIA

[nipper]

this is all over the place. i would never ever expect any oil to last 10,000 miles, i dont care what the mfg says. 6000 miles is pushing it, as about that time all the additives are gone. Since most people always let thier oil changer go a little farther then they should, i would say 5000. DO a search for this topic, you wil find tons of information pro and con. Longer oil change intervals also allow for small problems to become big ones. a leaking fuel injector that may get caught at a 3000 mile oil change can destroy and engine at 7000 miles or more on the same oil.

This is a case of penny wise dollar foolish, If you are doing it to save costs up front, it wil cost you later in an spun bearing. ALso another thing to remeber is that the filter may not be rated for 6000 miles, and you may still have to do a filter change before an oil change.

 

nipper

[Bmm001]

Good post, Nipper! We have never used synthetic in our cars, always regular dino oil (15w40), changed every 3,000 miles. All our subes have over 100,000 miles on them and we have never had ANY mechanical engine problems. I think if you stretch out the oil change intervals, even with synthetic, other minor problems tend to get overlooked, such as torn cv boots, a leaking gasket, irregularly wearing tires, etc. Because of the mileages on each car, it seems like one is always due for service (each car is about 3,000 miles apart in mileage), but we like the extra piece of mind knowing that the car is getting a thorough look-over every 3,000 miles.

 

Brian

[nipper]

yes that too. There is a post here with a blown engine, and we cant figure out why. i am thinking the long oil change interval had something to do with it. Not that the oil broke down, but that it had possibly leaky fuel injector, that diluted the oil and with a long chanege interval allowed the oil to be contaminated with gas and spun a bearing. with a 3000 interval may never had been an issue, or been caught in time.

 

Oil changes are so much more then just the oil, its checking the entire car with a quick look to make sure everythig is ok. You can caths so many thigs early before they leave you broke down on the side of the reoad.

 

nipper

[idosubaru]

interval is a generic number, there's really no "one-size-fits-all" mileage. person, car, age, mileage, condition of motor, usage of vehicle all make a difference. if the vehicle has any mileage on it then the only way to know is the have the oil analyzed professionally. also depends how long you plan on keeping the car or how honest you want to be on the resale of it.

 

the easy way is to pick a conservative number between 3,000-5,000 that you can live with and do that. the less i know about a motor the more i change the oil, that's my philosophy. i wouldn't go over 5,000 miles...can you do it, yes. is it worth it...

 

i have friends that have gone 10,000 on regular oil with no issues..yet. (oh, how nice not to have hydraulic valve lash adjusters..but i'm the one laughing when they need an adjustment). but that's a terrible idea. it does the engine no favors in terms of bearing, rings, valve train, cams...etc.

[NOMAD327]

Oil never breaks down in the conventional sense of the word, we have giant turbines at work that have been running twenty years on the initial oil fill. What happens in an internal combustion engine, is chemicals and solid particles are formed by combustion, and the contaminated oil is less capable of lubricating the engine. I called mobil 1 years ago on the subject, and they said the interval was identical to conventional oil. I had a new 88 camry, and the factory recommended interval was 10,000 miles for regular service. I have heard some of the new GM and German cars with oil wear monitoring computers will sometimes call for an oil change with mileage in the teens. I would never stretch my interval that far even though I do lots of highway miles. I like 5000 mile intervals, because I don't need a log book. just change at 5,000 10,000 15,000 20,000 etc. It's easy to keep track, and is a bit more conservative than manufacturers ratings, but not excessively so. I use synthetic in air cooled motors and turbocharged motors, but do not consider it necessary in regular engines. Severe or extremely dirty service would be another matter.

[Gnuman]

Engine oil is best described in two parts: the lubricant (oil) and the supporting chemicals (detergents, viscosity stabilisers, etc). Synthetics use a different lubricant than dyno-oils, an da different mix of supporting chemicals. When Emily hits 200K miles, I plan on doing a top engine overhual (I had originally planed on taking the whole thing down to bolts, but I'm a bit of a geek that way) and a complete reseal of the engine. When I do, I'll be switching to synthetic. What interval will I use? the same 3K/change. I'm going to synthetic for the better additives, and perhaps to prolong the supply of petrol we have available just a bit. (Ok, not by much but. . .) I could probably extend the interval even on the dyno oil I'm using now, considering that the oil is still fairly clean (I can see through it on the stick) when I change it. I maintain the "short" interval because that way I know my engine is protected. As for keeping a log, I make a note in my fuel log, and many auto parts stores give away windshield stickers that you write the change interval milage on (due when you have XXX miles).

[nipper]

Another way of looking at it, a few 100.00 more over thecars life, or a 2500.00 gamble on an engine ... i prefer the few 100.00 myself.

And what i meant by oil breaking down, i mean all the additives that are needed to keep things happy, sorry for the misunderstanding. But remeber you can bake oil, then it will start making carbon, then you have a paperweight..

 

More information then anyone would ever want to know

http://www.atis.net/oil_faq.html

 

(cant help it im an engineering tech and a virgo ..info junky)

 

nipper

[bfg9k]

this is all over the place. i would never ever expect any oil to last 10,000 miles, i dont care what the mfg says. 6000 miles is pushing it, as about that time all the additives are gone. Since most people always let thier oil changer go a little farther then they should, i would say 5000. DO a search for this topic, you wil find tons of information pro and con. Longer oil change intervals also allow for small problems to become big ones. a leaking fuel injector that may get caught at a 3000 mile oil change can destroy and engine at 7000 miles or more on the same oil.

This is a case of penny wise dollar foolish, If you are doing it to save costs up front, it wil cost you later in an spun bearing. ALso another thing to remeber is that the filter may not be rated for 6000 miles, and you may still have to do a filter change before an oil change.

 

nipper

 

Actually there is a way to tell what the best oil change interval there is for your car - a used oil analysis. You can buy an oil extractor pump that'll pull out the 3-4 oz you need, so you can get a UOA without changing the oil. Places like Blackstone Labs will then do a UOA for about $20.

 

The recommendation of the oil nuts over at www.bobistheoilguy.com with regards to extended drain intervals is this: do a UOA to determine what works best for your car, oil of choice, and driving style. You can't tell the condition of oil by its color or appearance. Go 3k, sample, test, repeat at 6k , whatever.

 

Subaru engines are very easy on oil, as it turns out, and extended drain intervals are certainly possible, as much as 10k or more - but test to be sure. Once my current run of Auto-RX (www.auto-rx.com) is finished next fall I'm going to give Castrol Syntec 0w-30 a try, run it for 5k miles, do a UOA, and then probably go to an annual oil change which is ~7k miles in my case.

[Setright]

6-7k miles. New oil and filter.

 

I change more often in summer, because trackdays tend to stress the oil more

 

(Even then I go 5k)

[rweddy]

6-7k miles. New oil and filter.

 

I change more often in summer, because trackdays tend to stress the oil more

 

(Even then I go 5k)

 

I agree, I run mobil one and change both oil and filter every 5k.

[jcniest5]

Thanks for all the replies. I think I'm gonna change it within the next ten days or so. It's nearing 4500 miles, so I think it's a good time to do it. Thanks again!

[Ranger83]

Actually there is a way to tell what the best oil change interval there is for your car - a used oil analysis. You can buy an oil extractor pump that'll pull out the 3-4 oz you need, so you can get a UOA without changing the oil. Places like Blackstone Labs will then do a UOA for about $20.

I learned about oil analysis in the Army where we pulled samples on our old Patton (diesel) tanks. I've been doing oil analysis on my old Subaru )97 OBW) and a Ford truck. They both curerntly have 165,000 miles. I use National Tribology - http://www.natrib.com.

 

At 7,500 miles the oil has been absolutely fine in both every time we've tested. It could go much, much, much longer but we don't bother. Many heavy trucks are going as much as 40,000 miles between changes but they have better filtration systems.

 

We use Purolator One or Mobil One filters as they are supposed to have synthetic elements, but at that interval just about anything will do.

 

There are still people who swear on a stack of Bibles that your car will burst into flames and/or major pieces will fall off at 3,001 miles. They have nothing to back this up except Faith. But it is a religious argument so save your breath. There are some good references above to read.

 

Car manufacturers would be risking major class-action lawsuits if their recommendations resulted in accelerated wear, but engines are lasting longer than ever. On our other 97 Subaru we used Castrol High Mileage and changed it every 5,000 because it's easy to remember.

 

Cold starts are one of the primary contributor to engine wear, so use your block heater if you have one!

[zyewdall]

Oil changes are so much more then just the oil, its checking the entire car with a quick look to make sure everythig is ok. You can caths so many thigs early before they leave you broke down on the side of the reoad.

nipper

 

Well, on old loyales, you need to add a quart every 1200 miles, so it gives you a chance to check even more frequently for anything falling off....

[rweddy]

Well, on old loyales, you need to add a quart every 1200 miles, so it gives you a chance to check even more frequently for anything falling off....

That is the truth!!

My brother has 220k on his loyale, and instead of changing the oil, he just keeps adding it in!

[wscheuer]

It's funny that you guys are quoting the 5000 mile mark as the bench mark for changing oil. Up here in Canada I was always told to change your oil every 5000 km's! Without getting out the calculator the difference is major. Perhaps the colder weather up here is a factor.

[Ranger83]

I used to work with a guy who came in one day to say his Toyota Celica (it was years ago) wasn't running too well: it was getting difficult to start. The guy was an Industrial Designer and kind of a space cadet. He had a long highway commute, about 40 miles one way a day.

 

When questioned, the Toyota had 69,000 miles on it. He was surprised to learn that maintenance was required - he was running on the original plugs, air cleaner - everything. It was around three years old!

 

He said that "the guy at the gas station" had added oil a few times and chastized him to "change it" so he bought a different brand the next time he added oil....

 

He b!tched about the $600 in repairs and maintenance he racked up but was just amazed at how well it ran - like a new car!

 

Just another example of the unsung heroes in Engineering.....

[nipper]

It's funny that you guys are quoting the 5000 mile mark as the bench mark for changing oil. Up here in Canada I was always told to change your oil every 5000 km's! Without getting out the calculator the difference is major. Perhaps the colder weather up here is a factor.

 

colder weather and fartehr driving distances. Heat is the biggest killer of engines, not cold.

 

 

nipper

[nipper]

I used to work with a guy who came in one day to say his Toyota Celica (it was years ago) wasn't running too well: it was getting difficult to start. The guy was an Industrial Designer and kind of a space cadet. He had a long highway commute, about 40 miles one way a day.

 

When questioned, the Toyota had 69,000 miles on it. He was surprised to learn that maintenance was required - he was running on the original plugs, air cleaner - everything. It was around three years old!

 

He said that "the guy at the gas station" had added oil a few times and chastized him to "change it" so he bought a different brand the next time he added oil....

 

He b!tched about the $600 in repairs and maintenance he racked up but was just amazed at how well it ran - like a new car!

 

Just another example of the unsung heroes in Engineering.....

 

 

hehehe i can tell you stories. US engineering technicians are the bridge between the mechanics and the engineers. Mechanics (good ones) would point things out to the engineers (since most of them never pulled a wrench in thier lives) but wouldnt listen to the mechnaics, But if one of us engineering techs told them the same thing, they would listen (silly little things like tool clearances for instance).

And dont get me started with rocket scientests, they should never be let out of the asalym except on testing day ....

 

nipper

[blitz]

More information then anyone would ever want to know

http://www.atis.net/oil_faq.html

From the first part written by Guy Burnham: " One problem you can have as mentioned by others is adding detergent oil to an engine that has a huge amount of deposits in it. As the detergent softens these deposits, there is a risk of a chunk coming loose and blocking something."

 

When was this written, 1943?

 

The second part is authored by Ed Hackett. Ed currently drives an '03 WRX and is a member of BITOG. Here's a used oil analysis submitted by Ed himself after taking the interval out to a mind-shattering 7521 miles:

 

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=002453#000010

 

Apparently Ed doesn't think 7500 miles is excessive.

[Setright]

colder weather and fartehr driving distances. Heat is the biggest killer of engines, not cold.

 

 

nipper

 

 

WHAT?

 

Cold starts stress the engine components because there is little oil present to protect them and the clearances are high.

Cold starts stress the oil because condensation inside the engine will mix with blowby and form acid. The oil has to "absorb" this before it attacts the engine surfaces.

 

Warm running engines have low clearances, plenty of oil circulation, and zero internal condensation. Ideal factors.

 

 

Overheating may kill engines, but running at operating temp will do no harm.

[bulwnkl]

I know that the "change it at 3,000 miles or else" phobia will persist perhaps forever, but I'd like to offer this:

 

Over the past several years (since 1999) I've used both synthetic and conventional oils in a variety of vehicles and have taken samples and sent them to the lab to see exactly what was going on. Prior to that (way back in the '70s) we used oil analysis on the oil in our tractor(s).

 

Using Mobil1 in a 1998 Dodge V-10 farm pickup in Yuma, AZ (it gets 125 F there), and SE Washington State under conditions of extreme dust, sand, mud, standing water, towing and hauling well above rated levels, and general farm (ab)use I ran 10,000 miles between drains and filter changes. The lab report showed excellent, low wear rates and plenty of reserve to go much further. I declined because 10,000 was an easy figure to remember.

 

I found precisely the same results under the same conditions with my '01 Toyota Tacoma V-6. In my modified '99 SAAB 9-3 I found the same ability with both Mobil 1 and RedLine. In our present Plymouth Neon I have found the same with Amsoil and RedLine. The cars did/do not see the same kind of service as the pickups, of course, but the Neon has made several very-high-speed trips through and around Nevada and southern Arizona at temperatures above 115 F during those long oil drain runs.

 

My XT6 has never been taken to an extended drain interval. I use it too infrequently, it uses/leaks too much oil, and I'm trying to get it all cleaned up. At this point I would increase the drain interval if it didn't go through as much as it does. It's hard to see pouring high-$ oil through it when it's a leaker/user.

 

There are very few driving conditions in North America which would NOT allow you to run 5,000 miles on $0.49/quart Chevron Supreme these days. Subarus are not 'sludger' motors so you don't need a synthetic for that. Super-short trips in sub-zero temps in the winter might require you to change more often than that in a Subie, but you'll never know if you don't test it.

[nipper]

WHAT?

 

Cold starts stress the engine components because there is little oil present to protect them and the clearances are high.

Cold starts stress the oil because condensation inside the engine will mix with blowby and form acid. The oil has to "absorb" this before it attacts the engine surfaces.

 

Warm running engines have low clearances, plenty of oil circulation, and zero internal condensation. Ideal factors.

 

 

Overheating may kill engines, but running at operating temp will do no harm.

 

i never said running at operating temp is a killer of engine. Heat, maybe i should have explained better. Cold is a huge stress of the electrical system Subarus, and some newer cars now, crank a little bit longer to get oil circulating before the car fires off to reduce wear at startup. Oil has a hard time flowing at -40C. Cold is easily corrected, heat is usually a run away event.

Cold water condensation, if following your point against mine, is not an issue as you said its operating temperature. Also with todays oils, its not as much an issue. If cold was as big an issue , we would all have dead cars by now. Alot of people here live in very cold winter climates.

HEAT is a killer of engines, todays engines run hotter then engines of yesterday, They run closer to the critical temperitures where cylinder heads warp, and oil thins out, and starts causing engine damage. Engines today can NOT be heavily overheated without causing the oil to thin out drastically. The thermostat in the car is at 170-180. Normal engine oil temp is about 220-230. After that the oil starts to thin out and the additives start to boil off. Now consider an engine that overheats. With a pressurized cooling system, the boiling point of the antifreeze mixture can be as high as 263F ( http://www.procarcare.com/icarumba/resourcecenter/encyclopedia/icar_resourcecenter_encyclopedia_cooling1.asp )

but any temp over 240 for an extenteded period of time will start to thin out and damage the additives in the engine oil. Oil in general takes longer to heat up and longer to cool down then antifreeze. Oil hotter then 240 will break down and cause oxidation. The crank journal is a hostile place, and damage occurs quickly once the oil gets that hot. This is why its important to minimize the time the car runs in the overheat range.

 

hope that explains it, sorry for maybe repaeating myself .. just came back from back shots, but this was anice mental exercise

 

nipper

[bulwnkl]

Nipper, I really respect you as a member here and get great info from you regularly. I hope what I am about to say is not taken as anything other than part of this one discussion.

 

First of all, most thermostats in new cars for the past several years have been 190-195 F, not 170-180. Next, I do not agree that most oil temps are 220-230. Most GM vehicles these days are equipped with oil-coolant heat exchangers that keep the oil temp quite close to coolant temp. If you can provide data to support the notion that oil sump temperatures are that high on average, please post it. I can tell you what the sump temperatures are in our Neon and XT6 during summertime (90-100 F) highway operation at 80mph according to infrared readings of the sump or filters (whichever is higher). The Neon runs ~195F under those conditions, and the XT6 is 205-210F. You can find an excellent digest of a study of coolant temperatures vs. oil sump temperatures AT WIDE OPEN THROTTLE here.

 

Next, those are temperatures in the sump. The temperatures of the various 'hot spots' in the engine are far, far higher than that. So, the oil is constantly being exposed to temperatures much higher. That doesn't mean the oil gets to those higher temps, but it gets part of the way there. So, in order for an engine to avoid coking into a carbon ball within a few hundred yards, the oil clearly is capable of dealing with these temperature cycles over and over and over again.

 

In another thread on here you posted that the additives in oil are worn out by 3,000 miles, even in synthetics. That is absolutely false. I posted data above showing it is false, and there are literally thousands of analyses that show such an assertion is false. Do you have any data to support that claim in a broad application?

 

Finally, I wish to add that main bearings and big-end bearings (lower rod bearings) are actually not very harsh places for oil. In terms of heat to the oil, most of it comes from under the piston crown. In terms of shear, the bearings are low-shear areas. The cylinder walls/rings are the high-shear areas of an engine, as are valvetrains in SOME engines.

 

I fully support everyone's decision to change oil however often they want to. Everyone should change it whenever they're comfortable doing so. Nevertheless, opinion and preference needs to be properly identified as such, rather than becoming confused with fact and data.

[friendly_jacek]

Nipper, I really respect you as a member here and get great info from you regularly. I hope what I am about to say is not taken as anything other than part of this one discussion.

 

First of all, most thermostats in new cars for the past several years have been 190-195 F, not 170-180. Next, I do not agree that most oil temps are 220-230. Most GM vehicles these days are equipped with oil-coolant heat exchangers that keep the oil temp quite close to coolant temp. If you can provide data to support the notion that oil sump temperatures are that high on average, please post it. I can tell you what the sump temperatures are in our Neon and XT6 during summertime (90-100 F) highway operation at 80mph according to infrared readings of the sump or filters (whichever is higher). The Neon runs ~195F under those conditions, and the XT6 is 205-210F. You can find an excellent digest of a study of coolant temperatures vs. oil sump temperatures AT WIDE OPEN THROTTLE here.

 

Next, those are temperatures in the sump. The temperatures of the various 'hot spots' in the engine are far, far higher than that. So, the oil is constantly being exposed to temperatures much higher. That doesn't mean the oil gets to those higher temps, but it gets part of the way there. So, in order for an engine to avoid coking into a carbon ball within a few hundred yards, the oil clearly is capable of dealing with these temperature cycles over and over and over again.

 

In another thread on here you posted that the additives in oil are worn out by 3,000 miles, even in synthetics. That is absolutely false. I posted data above showing it is false, and there are literally thousands of analyses that show such an assertion is false. Do you have any data to support that claim in a broad application?

 

Finally, I wish to add that main bearings and big-end bearings (lower rod bearings) are actually not very harsh places for oil. In terms of heat to the oil, most of it comes from under the piston crown. In terms of shear, the bearings are low-shear areas. The cylinder walls/rings are the high-shear areas of an engine, as are valvetrains in SOME engines.

 

I fully support everyone's decision to change oil however often they want to. Everyone should change it whenever they're comfortable doing so. Nevertheless, opinion and preference needs to be properly identified as such, rather than becoming confused with fact and data.

 

I can attest that this is the top notch and state of the art info!

 

I have a copy of engeenering paper that used radioactive chromium rings and clearly showed that the highest wear of the piston rings is during the engine warmup and goes down by the time operating temp is reached.

 

Interestingly, the wear is accelerated by high-sulfur fuel because of water condensation and sufuric acid production at low temp.

 

Many people buy the most expensive oil to protect engine and pay no attention to quality of fuel, clearly a poor judgement.

 

BTW, the reason modern engines warp easily is the fact that they are made from aluminium.