[mandown]

My Scion xB manual says oil changes are due every 6 months or 5,000 miles. It has been about 6 months and I have only logged about 2,000 miles (just shy of 17,000 miles total on my 2009). What do y'all think about getting the oil changed; do it, or don't it? The engine seems to be running fine, and I loaded up on synthetic oil last time.

 

[zdubyadubya]

I usually do whichever comes first on my subaru. I use synthetic and change at 7500 miles or once every three months.

 

[AngryMetalsmith]

So your oil has a shelf life like milk ? Weird

My toaster has an oil life percentage indicator and Honda recommends changing it at 15%. I changed it at 30% and 5k miles.

 

[buildyourown]

I'm a miles guy. On my low mileage vehicles, I'll go a whole year since it's not even 5k. I think if you drop $50 on premium synthetics, they can handle this. Cheap dino, I'd be worried about.

 

[eaterofdog]

My understanding is the time limitation is to prevent moisture build up in the oil. As long as the car gets completely warmed up when you do drive it, it should be fine.

 

[mandown]

My understanding is the time limitation is to prevent moisture build up in the oil. As long as the car gets completely warmed up when you do drive it, it should be fine.

i assumed there had to be a reason for the time factor, since oil doesn't stike me as the kind of stuff that spoils on the shelf.

 

[kazlx]

In southern cali, I wouldn't worry about it. I'd maybe change it once a year if you don't hit the mileage mark. As long as you are relatively diligent about it, the car will be fine.

 

[eaterofdog]

i assumed there had to be a reason for the time factor, since oil doesn't stike me as the kind of stuff that spoils on the shelf.

The thinking is people who don't put many miles on the car tend to take very short trips. The oil never heats up enough to boil the water off.

 

[IH8Rice]

this was actually in the news the other day
http://www.autoguide.com/auto-news/2011/12/california-wants-you-to-go-longer-between-oil-changes.html


edit: i go by mileage, especially when i hardly drive one of my vehicles. i typically change at 7500miles

 

[Montana rider]

synthetics absorb less water than standard oils -- the old recommendations don't really apply anymore re: miles/time as most manufactorers have grudgingly admitted.

 

[stevew]

my cars have done well with little to maintenance on my part and they have all been vw's.

go figure.

the only ones that died are the ones i wrecked.

 

[CBJ]

this was actually in the news the other day
http://www.autoguide.com/auto-news/2011/12/california-wants-you-to-go-longer-between-oil-changes.html

My 2007 Volvo XC70 the manual says 7500 and that is what the site also recommends. I do think I changed it sooner this time but the mechanic said the oil looked like it needed a change - really?

 

[IH8Rice]

My 2007 Volvo XC70 the manual says 7500 and that is what the site also recommends. I do think I changed it sooner this time but the mechanic said the oil looked like it needed a change - really?

hmm, im guessing my manual says something similar then but i never bothered actually reading it. 7500 is what i usually did anyway. hell, ive gone 15k on my old company cars without any issues (not that i cared if there was)

your mechanic probably thought your oil looked fairly dark which is why he probably said that. its a not-so-scientific method of checking. (and what i sometimes do)

 

[jdcamb]

Oil, I knew I was forgetting something. They should really have Oil Gauges in cars... That dipstick doesn't tell me anything, after I clean off the black gunk it doesn't show anything. POS! I put oil in and it just leaks all out by the back of the motor.

 

[Sandwich]

Always judge based on the use of the oil. Stop and go traffic? Shorter intervals. Highway miles? Go longer. I think every six months is a reasonable estimate for a regular oil change. What does it really cost you to do the work? $50? $100 a year is small peace of mind compared to replacing an engine or degrading mileage.

 

[eaterofdog]

Even if you never change your oil, the problems have more to do with the system gunking up than lack of lubrication. The mains and cams are fluid bearings, where lubrication only matters at startup.

When I was a kid, we had an old equipment motor and we put various things in the crankcase in place of oil, trying to kill it. Even water works until it boils. (When it would seize, we would spray everything with wd40 and break it loose with a breaker bar.)

 

[IH8Rice]

They should really have Oil Gauges in cars... That dipstick doesn't tell me anything, after I clean off the black gunk it doesn't show anything. POS! I put oil in and it just leaks all out by the back of the motor.

more and more new cars dont have dipsticks anymore, they have the computer tell you when to do it

 

[jdcamb]

more and more new cars dont have dipsticks anymore, they have the computer tell you when to do it

Who? As you have witnessed, I invented it. Dirt are you busy?

 

[johnbryanpeters]

So your oil has a shelf life like milk ? Weird

My toaster has an oil life percentage indicator and Honda recommends changing it at 15%. I changed it at 30% and 5k miles.

My Fit asks for an oil change about every 11,000 miles.

 

[CBJ]

My Fit asks for an oil change about every 11,000 miles.

Does it ask nicely?

 

[DirtyMike]

The low down


Whichever comes first..... First off throw away the recs you see, look at the severe schedule, then look at what will put your vehicle into the severe conditions schedule...... Might find that you are in need of oil changes sooner than either the time or milage as reccamended....


As far as to why.... its simple, once you start to get crap in the oil, IE fuel blow by, carbon build up ETC..... the additives that make the oil work are "activated" so to speak.... They keep attacking the stuff that gets into your oil forever....... Biggest reason for time frames instead of miles is the anti foaming agents wear out... foamy oil is bad... next one is the additive that makes the oil stick to the metal instead of sliding back to the oil pan..... Dry starts are bad..... another additive that breaks down is the particulate additive, this suspends solids to keep it from becoming engine gunk... engine gunk bad, when this additive breaks down **** sticks inside the engine, instead of flowing out with the oil<talking smaller stuff than the filter will stop>.


Its never been about water/moisture build up in the engine... that boils off every tim eyou run the vehicle.

Synthetics or not, its still not the oil itself that goes bad, its the additives that make it work that wear out..........

So you ask miles or months.... the answer is both... whichever comes first



The real problem is that if you wait because everything seems fine, you will cry when it isnt, because then it is too late..... An oil change is one of those things you dont want to wait "till you need it".... You never want to find out at 50K miles that you need an engine because you should have been changing the oil every 4k instead of 7500<example>

 

[mandown]

epic drunken mobile phone post.

The low down


Whichever comes first..... First off throw away the recs you see, look at the severe schedule, then look at what will put your vehicle into the severe conditions schedule...... Might find that you are in need of oil changes sooner than either the time or milage as reccamended....


As far as to why.... its simple, once you start to get crap in the oil, IE fuel blow by, carbon build up ETC..... the additives that make the oil work are "activated" so to speak.... They keep attacking the stuff that gets into your oil forever....... Biggest reason for time frames instead of miles is the anti foaming agents wear out... foamy oil is bad... next one is the additive that makes the oil stick to the metal instead of sliding back to the oil pan..... Dry starts are bad..... another additive that breaks down is the particulate additive, this suspends solids to keep it from becoming engine gunk... engine gunk bad, when this additive breaks down **** sticks inside the engine, instead of flowing out with the oil<talking smaller stuff than the filter will stop>.


Its never been about water/moisture build up in the engine... that boils off every tim eyou run the vehicle.

Synthetics or not, its still not the oil itself that goes bad, its the additives that make it work that wear out..........

So you ask miles or months.... the answer is both... whichever comes first



The real problem is that if you wait because everything seems fine, you will cry when it isnt, because then it is too late..... An oil change is one of those things you dont want to wait "till you need it".... You never want to find out at 50K miles that you need an engine because you should have been changing the oil every 4k instead of 7500<example>

 

[DirtyMike]

Ummmm no........ Just a post from a laptop while drinking........ A laptop in serious need of a new keyboard

 

[mandown]

period surplus and deficiency. so good.

Ummmm no........ Just a post from a laptop while drinking........ A laptop in serious need of a new keyboard

 

[skyst3alth]

My grandfather, Dad, and I all changed our oil at 5k miles - never had an issue across three generations in terms of oil.

Smashing cars into telephone poles and buildings on the other hand, we've got that well covered.

 

[blackohio]

i've done 3K, 5K and 10K after seeing someones oil result results of good synthetic. little difference between 5 and 10 if you car isn't shedding metals.

 

[lovebunny]

period surplus and deficiency. so good.

he just figured he would lay them all out in a row and you could put them where you like

 

[eaterofdog]

DM, Where are the additives going? Evaporating? If they were that volatile, they would boil off the first time the oil hit 300 degrees. Oxidizing? Again, they would completely oxidize the first time they got hot. Why can oil sit on the shelf but not in an oil pan?

 

[Sghost]

Its your filter that needs changing. Not too many people replace the filter, add the old oil back, then top it off though.

 

[CrabJoe StretchPants]

For me, miles in the car and months in the Jeep. I drive about 500 miles/week in the car, so it's an oil/filter change about every 10 weeks. The Jeep only sees about 4-5k miles a year now, so it's an oil/filter change every 6 months.

 

[DirtyMike]

DM, Where are the additives going? Evaporating? If they were that volatile, they would boil off the first time the oil hit 300 degrees. Oxidizing? Again, they would completely oxidize the first time they got hot. Why can oil sit on the shelf but not in an oil pan?

They dont go anywere, they are still in the oil. It is the combination of the heat, and contaminants that break the additives down. Remember that additive I spoke of which suspends solids in the oil, thats why it doesnt oxidize onto the sides of the engine, and also why you want to change the oil before you are in "need"

For the record, I wouldnt use a bottle of oil that has been sitting on a shelf for a year or more either

Our standard rec's for our shop, being based in southern california, basing of the normal rec's in an owners manual for severe service< havent had a vehicle in Socal that doesnt end up in this catagorie yet>. Also these recs are given to us by our oil supply company, they do alot of testing in diffferent vehicles I trust their judgement<not an oil company just the supply company>

three months three thousand for conventional oils
Five months five thousand for low cost synthetics<shell, fram ETC>
six months six thousand for mobil one

Its your filter that needs changing. Not too many people replace the filter, add the old oil back, then top it off though.

Ummmm..... What? Yeah your filter needs changing but I am just very unclear as to your source that not many people change their filter.

There was a theory for a long time that if using a synthetic oil you can just change the filter and top the oil off. The theory was that the top off of oil was enough to "recharge" the additives in the oil. It has been proven a very much so big failure.

 

[eaterofdog]

Also these recs are given to us by our oil supply company

Okey dokey.

 

[Heidi]

I probably only drive my car 100 miles a year. I guess I'll never have to change the oil!

 

[DirtyMike]

Okey dokey.

Think of it like mixing baking soda and vinegar. Obviously on the extreme of reactions here but its a good example. You have some baking soda, you add the vinegar and get a reaction. Afterwords you still have a mix of baking soda and vinegar, just neutralized and still there.

Or think of it as when you put baking soda in teh fridge for odors, eventually you have a box of baking soda that is just that, a box of baking soda that has taken on its capacity of odors.... But you still have a full box of baking soda.

 

[CrabJoe StretchPants]

I think he was LOLing at the fact those recommended service intervals were from the people selling you oil. Meaning he's surprised they didn't say you need an oil change every other time you use your car.

 

[IH8Rice]

Not too many people replace the filter, add the old oil back, then top it off though.

if people dont replace the filter when doing an oil change then they deserve whats coming to them

 

[syadasti]

Or think of it as when you put baking soda in teh fridge for odors, eventually you have a box of baking soda that is just that, a box of baking soda that has taken on its capacity of odors.... But you still have a full box of baking soda.

That is a marketing ploy to help sell baking soda, only a small portion of the box is used. Hopefully you aren't getting all your oil knowledge from the suppliers:

baking soda does not eliminate odors very well at all. As a wash solution, it is mildly alkaline and can serve to cut grease when dumped down a drain. However, crystal Drano is much more effective -- and far more dangerous to use. The popular "open box of Arm & Hammer in the refrigerator" simply provides an adsorbent material that can soak up odors -- but not very effectively. For example, if some of the odoriferous materials floating around in the refrigerator are acidic, the alkaline baking soda can absorb and neutralize the acid. Even in that regard, it is not all that effective because, as the powder in the box contacts water vapor, it tends to crust over an lose a great deal of its already limited surface activity. It all sounds quite nice, but it does not work very well. Far better would be a canister of activated charcoal because it can indeed adsorb vapors that contact the charcoal.

 

[DirtyMike]

That is a marketing ploy to help sell baking soda, only a small portion of the box is used. Hopefully you aren't getting all your oil knowledge from the suppliers:

Not at all, I actually do oil breakdown tests in the shop, also fuel breakdown tests as well. I can tell you what condition yourinternal engine parts are in with an oil sample, and the broken down viscosity when we are doing the sample. I can also give you an ethanol content Etc Etc........

What most people dont know is that most vehicles the oil filter is long since plugged and running in bypass mode when you run till 5k on an oil change. There is substantial reasons to change you oil before it is actually due, more than I care to list here but for 25 bucks for conventional its well worth not taking the risk.



Oh and for those that were talking about oil absorbing water, oil doesnt absorbs water at all. They dont like each other be it conventional or synthetic. It doesnt exactly mix either but it will become a nasty foamy substance that it about the slickest thing you can walk on when its on the floor in the shop.

One of the other really important additives is that which gives the oil its viscosity as well, you know the oils thickness? Its not like they are finding different oil supply for different viscosities, it all comes from a single batch. All oils do get thinner as you use them, yet another good reason to not take a chance<Someone alrady mentioned that your mains and rods are actually a fluid bearing when the vehicle is running>.


I think carbon in an aquarium filter is a better example actually. Used to keep water odor down and keep water clarity up as it becomes used up the water gets cloudy. If you look in the filter you still have all the carbon in it, yet its no longer doing its job. Doesnt go anywere, but its still in need of replacement

 

[syadasti]

I think carbon in an aquarium filter is a better example actually. Used to keep water odor down and keep water clarity up as it becomes used up the water gets cloudy. If you look in the filter you still have all the carbon in it, yet its no longer doing its job. Doesnt go anywere, but its still in need of replacement

It mentions activated charcoal in the quote above, much better than baking soda but like you said when all the adsorption sites are used it has to be replaced....

http://en.wikipedia.org/wiki/Activated_carbon#Applications

 

[DirtyMike]

I was jsut using examples so people are understanding the additive in oil are not going anywere, but they are simply no longer doing their jobs and need to be replaced is all. I had no care to go so far as to explain how these examples do their job!!!


Oil content/breakdown tests are fun BTW, I get to play chemist.