# Two auto questions...



## farmerjohn1324 (Jul 28, 2015)

1. Why is there a lot of "yellow stuff" underneath my car. There are no active leaks. Is this normal? Or the result of a previous leak?

2. I've always heard to change oil every 3000 miles. The shop I go to just told me to wait 4000 miles because I use high mileage oil. I've been reading online that the 3000 mile thing was promoted by companies that manufacture motor oil to increase sales. My Haynes Manual tells me every 3000 miles. How often should I change it?


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## chandler48 (Jun 5, 2017)

The yellowish stuff looks to be dried antifreeze residue. What model car are you talking about? Certain older cars required more frequent oil changes. That span has increased over the years. Changing the oil really depends on the condition of the oil and the environment it is run in. Long dusty country roads may dictate a more frequent oil change schedule, while flatland suburban drives can extend that interval. I believe my wife's 2013 Honda CRV is set at 4000 miles.

I drive a Cummins diesel and when I check the oil, if I can't read the marks on the dipstick through the oil, I change it. Of course diesels are tougher on oil than gassers.


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## farmerjohn1324 (Jul 28, 2015)

chandler48 said:


> The yellowish stuff looks to be dried antifreeze residue. What model car are you talking about? Certain older cars required more frequent oil changes. That span has increased over the years. Changing the oil really depends on the condition of the oil and the environment it is run in. Long dusty country roads may dictate a more frequent oil change schedule, while flatland suburban drives can extend that interval. I believe my wife's 2013 Honda CRV is set at 4000 miles.
> 
> I drive a Cummins diesel and when I check the oil, if I can't read the marks on the dipstick through the oil, I change it. Of course diesels are tougher on oil than gassers.


Yes, I thought it was antifreeze residue.

2000 Chevy S10 2.2L Automatic. I live just north of Orlando, FL. I drive about 450 miles/week. Currently using 5w30 high mileage.


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## bassadict69 (Jul 21, 2011)

I use synthetic 5w30 in my silverado 4.8 liter...I have even went as far as sending an oil sample once at 7500 miles on the oil and the oil test results looked great! The oil lab even recommended going another 2500 miles next time and sampling. I have trouble going that far though.


I normally changed it at about 8000 miles which ends up being about every 7 months. The truck has 240,000 miles on it and is going strong. 



Even with regular oil, I feel based on my research and seeing others lab results that every 3000 miles is WAY overkill!


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## mark sr (Jun 13, 2017)

You should be ok changing the oil at 4k. I change the oil every 3500 miles on my 2010 jeep [2-3 times a year] but my wife's new maxima gets changed at 5k [full synthetic] My old truck just gets changed once a year but that is usually 3k or less.


btw - I used to live east of orlando.


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## farmerjohn1324 (Jul 28, 2015)

bassadict69 said:


> I use synthetic 5w30 in my silverado 4.8 liter...I have even went as far as sending an oil sample once at 7500 miles on the oil and the oil test results looked great! The oil lab even recommended going another 2500 miles next time and sampling. I have trouble going that far though.
> 
> 
> I normally changed it at about 8000 miles which ends up being about every 7 months. The truck has 240,000 miles on it and is going strong.
> ...


I'm unfamiliar with oil labs. Where do I find one of those? I thought the only way was to eyeball it.

Since I haven't been using synthetic up to this point, would it cause problems to switch to synthetic now?


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## mark sr (Jun 13, 2017)

You are probably using a synthetic blend currently. It doesn't hurt to switch to fully synthetic although it is possible you might develop oil leaks - if you do it's no big deal to change back the next oil change.


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## farmerjohn1324 (Jul 28, 2015)

*Three auto questions...*

Here's a third question without starting a new thread...

Should I be concerned about lots of water dripping off my accumulator? Last night I was parked for 10 minutes and have a whole river of water underneath my car.


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## bassadict69 (Jul 21, 2011)

farmerjohn1324 said:


> I'm unfamiliar with oil labs. Where do I find one of those? I thought the only way was to eyeball it.
> 
> Since I haven't been using synthetic up to this point, would it cause problems to switch to synthetic now?




I have always used Blackstone Labs...


Some people do have the leak issues, but most have no problems at all.


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## Bob Sanders (Nov 10, 2013)

farmerjohn1324 said:


> 2. I've always heard to change oil every 3000 miles. The shop I go to just told me to wait 4000 miles because I use high mileage oil. I've been reading online that the 3000 mile thing was promoted by companies that manufacture motor oil to increase sales. My Haynes Manual tells me every 3000 miles. How often should I change it?



"High mileage oil"? Don't believe the claims.



Oil doesn't necessarily go bad. Some of the additives may break down over time but that's another story.


The primary reason why oil is changed is because that's really the only way we can clean the inside of the motor on any regular basis. Crud from the combustion process mixes with the oil and is removed with each oil change. The longer you go without an oil change the more that crud is allowed to do damage to the inside of the motor, so changing oil comes down to merely a balance between your wallet and how clean you want to keep the inside of your motor.


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## Brainbucket (Mar 30, 2015)

*Re: Three auto questions...*



farmerjohn1324 said:


> Here's a third question without starting a new thread...
> 
> Should I be concerned about lots of water dripping off my accumulator? Last night I was parked for 10 minutes and have a whole river of water underneath my car.


That's normal. :vs_cool:


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## Brainbucket (Mar 30, 2015)

You might extend oil change intervals but remember, oil filters stop filtering around 3000 miles. you can wait for 7500 mile before changing oil but you gotta change the filter at 3000 miles or so no matter what they say. For example, the oil filter on a Chevy 4.8, 5.3, 5.7, 6.0, 6.2, the filter is as big as your fist but a 1983 454 oil filter is as big as a coffee can. Huge difference but yet they filter the same amount in the same period? NOT!!:vs_cool:


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## bassadict69 (Jul 21, 2011)

Brainbucket said:


> You might extend oil change intervals but remember, oil filters stop filtering around 3000 miles. you can wait for 7500 mile before changing oil but you gotta change the filter at 3000 miles or so no matter what they say. For example, the oil filter on a Chevy 4.8, 5.3, 5.7, 6.0, 6.2, the filter is as big as your fist but a 1983 454 oil filter is as big as a coffee can. Huge difference but yet they filter the same amount in the same period? NOT!!:vs_cool:



The filter is the only reason I do not go longer than what I do. I firmly believe based on lab results that the Mobil 1 synthetic I use could go close to 15,000 miles. Based on my samples and measurement of particulates or whatever they measure, they recommended changing the filter about every 7000 miles. I do think all engines are different and no real way to tell without a sample, but like the oil, I believe filters are good for way over 3000 miles.


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## F250 (Feb 13, 2018)

Bob Sanders said:


> "High mileage oil"? Don't believe the claims.
> 
> Oil doesn't necessarily go bad. Some of the additives may break down over time but that's another story.


There is some truth to what you shared, but not all of it. I've been a chemical process engineer for over 30 years in large manufacturing plants (not petroleum), and spent a 4-year stint working as a lubrication specialist. 

Oil DOES go "bad" as a result of oxidation, shear forces, and inefficient filtration. Additive break down is the loss of anti-foaming agents, detergents, viscosity modifiers, and extended friction modifiers. When any or all of these components get used up, your oil will "misbehave" in the heat of the fight -- literally -- and your oil will get "weaker and dirtier". Your oil filter is meant to keep the loose, insoluble combustion byproducts from dirtying up your engine internals, but carbon/char/asphaltine can build up inside the combustion chambers, and this is virtually always because either the oil has been run too long or the wrong grade of oil has been used. 




Bob Sanders said:


> The primary reason why oil is changed is because that's really the only way we can clean the inside of the motor on any regular basis. Crud from the combustion process mixes with the oil and is removed with each oil change. The longer you go without an oil change the more that crud is allowed to do damage to the inside of the motor, so changing oil comes down to merely a balance between your wallet and how clean you want to keep the inside of your motor.


Again, some truth, but not complete. The primary reasons that oil needs to be changed is actually two-fold. First is keeping the additive package in play so that the carbon/char/asphaltine contaminants are kept at a minimum. The second reason is actually the first one which your engine will generally see and be hurt by, and that is the fact that all oils eventually "shear" down to lower-than-needed viscosity. The lower the viscosity, the lower the film strength. The lower the film strength goes, the easier it is for friction surfaces to break through the super thin barrier film of lubricant and result in metal-to-metal contact -- really bad juju for your engine parts!

Oil analysis will tell you three critical conditions about your used engine oil, and typically runs in the $20 to $30 per sample at Blackstone (other used oil lab services are available from OilGuard, Schaeffer, CAT, etc.):
1) How far has your oil's viscosity been compromised?
2) Are your additives still in a serviceable concentration?
3) Are wear metals (Cu, Fe, etc.) beginning to show up?

Reaching acceptable limits on ANY one of the three issues above should dictate the limit of how long you can run your oil, and they are all affected by your own individual driving style, engine design, and quality of oil used in the engine.

For example, using an oil bypass filtration system (4 micron) and high quality synthetics used to enable me to run 18,000 miles between oil changes on my diesel because it was primarily highway miles without towing anything (18,000-20,000 miles per year). Now, most of my trips are only 5-6 miles at a time and only about 8,000 miles per year, so I'm back to 8,000 mile oil changes in order to keep my oil's viscosity in the correct range (at that point, the additives and wear metals all remain within tolerance, but the viscosity is the first characteristic to be compromised. Extended oil drain intervals are very important to me because my truck takes 4 gallons of oil and two oil filters per change, but I will not run it so long that it creates internal wear problems, and I'm still running original fuel injectors, high pressure oil pump, and turbocharger at 300K miles. 

So, does everyone need to run used oil analysis (UOA)? No, because you can simply adopt an early oil change philosophy, and that is what you mentioned, too, Bob -- a means of avoiding future problems is just a balance between emotional comfort and money. Waiting too long, though, has well-documented negative side-effects. If you want to pinch your pennies, run a few consecutive UOA's at the onset of getting a vehicle, and then once yearly afterwards. Again, though, for the cost of most oil changes (4-6 quarts and a filter), UOA's are not worth it if you follow manufacturer-recommended change intervals. 

For me, though, the combination of 4 gallons of oil and two filters per change is quite an incentive to truly know my mileage limits.


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## ChuckF. (Aug 25, 2013)

Re yellow stuff, keep your coolant overflow tank at the required level and check it regularly to see if you are losing any. You can have leaks in places where the leak is being evaporated away by a hot cylinder head or exhaust before it can puddle on the ground.


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## Bigplanz (Apr 10, 2009)

I use 5W20 and change it every 5K miles. If I towed with it, I would use 5W30 and change it more frequently. I check it every couple of weeks and keep it at the full mark. It uses less than a quart between oil changes.

My Navigator has the 5.4L V8. If it had the 3.5L turbo V6, I would use full synthetic and change it every 3K.


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