changing your oil too often will harm your engine

Status
Not open for further replies.
Joined
Apr 28, 2010
Messages
36
Location
Australia
found this interesting post on another forum.

http://www.ozmpsclub.com/forum/tech-talk/1446-oil-type-changes.html

here is a cut and paste to save time. is there any truth at all to this claim? never heard of it TBH!


QUOTE FROM ABOVE
Save your money and save your engine
A lot of the advice above is typical forum-perpetuated myth. Someone on this forum recently stated that it can't hurt to change your oil too often. Unfortunately that couldn't be more wrong.

The Problem
5000 km change intervals are harmful to your engine and our DI engines are even more vulnerable to the type of damage done by over servicing than PFI engines.

Why does the problem exist?
It's a cultural thing that arose in the US and was driven by marketing and profit making. The consequent myths and consumer expectations are now entrenched. The cultural gap is now so broad than in the US a car may have an 8000km OCI, while the same model, from the same production line, might have a 20,000 km OCI when sold in Europe where people aren't affected by the myths.

Why it's OK to follow the manufacturers service interval
All synthetic oils are capable of exceeding the manufacturers recommended OCI by at least 50% or more. It's incorrect to suggest the oil could break down or succumb to sludge any earlier.

People using oil analysis reports to justify over servicing aren't reading them correctly. None of the reports that I've seen on DISI engines have shown oil that has reached condemning limits in terms of insolubles and oxidation. As for the solubles, if they are excessive, you need to drive the car further, not change the oil.

The references to carbon contamination are also incorrect. People naturally assume that black oil is unhealthy, when the opposite is true. The colour of the oil is an indication of how well it's doing its job. The darker the better (up to a point not exceeding the manufacturers OCI).

If you had a problem with contamination (not that you do, but if you did) the solution is to change the oil filter, not the oil.

Why is it harmful to change the oil too frequently?

In a word; volatility. Oil volatility is at its greatest in the first 3000km after an oil change. After that the volatility reduces and the oil stabilises.

Volatility is particularly bad for a DI engine because all of the lost fractions exit via the PCV system. Much of it goes out through the rocker cover vent, into the intake, through the turbo compressor and intercooler, then puddles in the bottom of the inlet manifold where it combines with the stuff coming through the PCV valve to coat the inlet valves and combustion chambers in gunk.

That black soot you see in your exhaust pipes, don’t assume it’s all caused by rich mixture. Excessive oil changing will contribute more soot.

The presence of oil in the intake also lowers the octane rating of your fuel leading to detonation.

The NOACK volatility test quantifies the extent of oil evaporation. The test standard - ASTM D5800 - 08 Standard Test Method for Evaporation Loss of Lubricating Oils by the Noack Method – also hints at another kind of danger associated with frequent oil changes where it states “Procedure C, using the Selby-Noack apparatus, also permits collection of the volatile oil vapors for determination of their physical and chemical properties. Elemental analysis of the collected volatiles may be helpful in identifying components such as phosphorous, which has been linked to premature degradation of the emission system catalyst.”

A lot of phosphorous is lost in the initial boil-off phase of new oil and it’s likely to be harming oxygen sensors and cats.

Engine manufacturers understand the problem and it would be easy for them to identify the type of damage done by over servicing and potentially result in a warranty claim denial.

Summary
By changing your oil at 5000km, you are subjecting your engine to oil that is almost always in the initial boil-off phase. It's contaminating and filling your engine with gunk. Contrary to popular and uninformed opinion, oil that is 10,000 km old is not likely to be harmful, and would certainly be less harmful than fresh oil.

I've never changed my oil more frequently than the specified 10,000 km OCI and my engine is in perfect condition after 106,000 km with no problems with contamination, gunk or soot.

When my warranty expires I would have no qualms running my oil out to 12,500 or even 15,000 km providing an oil analysis indicates that insolubles and oxidation are not excessive. And I'm sure my engine will thank me for it by remaining in peak uncontaminated condition.
 
Lots of technical information there, but no links to back it up.

I know a guy that runs a small fleet of aircraft, changes the oil every 25 hours, and has has engines rebuilt with 2000 hours and negligible wear. If what's listed above was true, I'm sure they would have been toast inside, or failed prior to the rebuild.

IMO fresh oil is good for your engine; but with the quality of oil so high these days, you can go longer OCI.
 
it's been awhile since chemistry class, but I am pretty sure that zinc does not "boil off".

and anyone with a chrysler or dodge 2.7L engine (or many other examples) would be best advised to NOT adhere to adhere to this opinion. in fact, a friend had to pay to replace the engine on his durange at 44k miles. he generally did 5k OCI's. all sludged up, so no warranty. period. I'd like to hear this "experts" take on sludger motors. it's easy to write a story. it takes alot more to do it with knowledge, balance, and facts. of course, this is just my opinion.
 
Quote:
I've never changed my oil more frequently than the specified 10,000 km OCI and my engine is in perfect condition after 106,000 km with no problems with contamination, gunk or soot.


My uncle drank a 5th of gin and smoked 3 packs of cigarettes a day and lived into his 80s. That doesn't mean that being an alcoholic and heavy smoker are good for you.

Not that a 6000 mile oci is exceptional or that engine condition at 65,000 miles means that you doing anything particularly good.
33.gif
If the lad believes you can draw conclusions on engine maintenance by the fact that an an engine operates correctly at 65k miles, then he doesnt know how long engines normally last.

Originally Posted By: fredjacksonsan
Lots of technical information there, but no links to back it up.



Fred, you are too kind, that was techno-babble, not technical information.
cheers3.gif
 
aircraft engines (or oil) bear almost no relationship to automotive engines (especially DI engines as he is specifically referencing). aircraft engines dump the crankcase gasses overboard through the "whistle tube", no PCV, no recirc. also because aircraft engines run at a different profile, 25hrs on an aircraft engine is not comparable to 25hrs on a auto. finally, since there are only 3 brands of oil certified for reciprocating aircraft engines in the US, with similar usage profiles, you should get similar results.

some of his points "seem" to be reasonable. we all know that DI engines are having some issues, and low SAPS oils seem to be where they are going. starting off with a low volatility oil would probably help, but certainly after 3k or so most of the boil off has already happened. this parallels the conoco study that showed that engine oils actually get better after about 2k of use.

not saying he is right, but the examples given for why he is wrong bear no relevance.
 
The OP assertions with the DISI engine seem reasonable** But if you are using a low volatility oil, then most would not apply. I think Cheetah summed things up well.

** with this exception:
"Engine manufacturers understand the problem and it would be easy for them to identify the type of damage done by over servicing and potentially result in a warranty claim denial."
 
Last edited:
I think the only problem with changing oil too often is the expense, and wear and tear on the drain plug. LOL Clean oil is better than dirty oil, find a happy medium and stay with it. The OM is a good place to look for suggestions. JMO
 
Due to high detergent action and surface competition fresh oil will show much higher wear for the first 1000km on a hard driven engine. Does not anyone here understand detergent v. ep/aw/fm?!
 
It might show higher wear #'s early on but IIRC it wasn't really ever proven to be wear. It could be more cleaning done by the fresh add pack, I believe I might have read that here. Maybe not in those exact words though.

Anyone else read that?
 
Unfortunately especially in the context of the writing, the story above is not terribly relevant. The reality is that in the US, we do nt operate DI engines the same way. We are willing to sacrifice tons and tons of gasoline and CO2 emissions for a tiny bit of NOx emissions. SO we do not run lean stratified charge, we run rather rich, and have different operating considerations to make.

Volatility is something to consider, and the solvent action of the volatiles (though IMO diluted fuel will be as bad) may cause some of the adds to come off, though boil off isnt the right explanation. That said, all oils have a distribution of volatiles, and so there is more to consider there. An oil that will flash off 5% should only loose half as much per OCI as an oil that looses 10%. Does this mean that the effects of double OCIs for the lower volatility oil should equate to single OCIs for the higher volatility oil? Does NOACK really mean anything practical with respect to oil consumption? Ive never seen 10% loss of oil in vehicles where Im running an oil with that kind of NOACK result. My losses are generally not measurable across an OCI in tight engines such as my saab. So is all that volatility truly relevant in full in all applications?

Some good points but a lot to consider against it too.
 
Quote:
it's been awhile since chemistry class, but I am pretty sure that zinc does not "boil off".


I wouldn't necessarily use that term, but it's the volatility of zinc/phos that makes longer term cat poisoning a (non) concern ...so it's more or less a given. What it amounts to in significance is the only debate (from that isolated angle).

..but in tethering that to the referenced text, let's grant that most zddp has a % of volatility. The lower add oil that's changed more frequently may be processing MORE zddp through the engine.

The basic premise is that the deposits are from volatile components in the oil. Some are from the oil itself and others are introduced and reintroduced via the characteristics of the DI design. Since the introduction of the fuel components is unavoidable, the only way to reduce deposits is to limit amount of volatiles present in the oil. Changing the oil more often merely processes even more volatiles through the engine, adding more deposits.
 
Originally Posted By: Gary Allan
Quote:
it's been awhile since chemistry class, but I am pretty sure that zinc does not "boil off".

Changing the oil more often merely processes even more volatiles through the engine, adding more deposits.


How would that effect engine life? I still believe aside from possibly killing the cat, something I've never done,,,,yet. I don't see much downside other than wasting some money, and resources. I think the wear metals spoken about are from the fresh oil doing some cleaning of deposits left from the older dirty oil.
 
Quote:
How would that effect engine life?


It won't. The quoted text is dealing with valve deposits in the dry intake of DI engines. So "engine life" isn't the issue, per se~. It's side effects and complications.


Quote:
I still believe aside from possibly killing the cat, something I've never done,,,,yet. I don't see much downside other than wasting some money, and resources.


Agreed. This is a policy issue. 30 million people changing oil @ 3k/3m with SL vs. 30 million changing oil @ 3k/3m with SM. Less cat poisoning.

Quote:
I think the wear metals spoken about are from the fresh oil doing some cleaning of deposits left from the older dirty oil.


I don't know if it would be "cleaning" per se~, but disruption of an older film formation in the seating of the new could spike metals that were entrained in the old formation. That is, no "new" metal is being introduced into the sump, just stuff that was sequestered. ..but whatever the origin, I can't see it having any origin that could justify the term "wear".
 
Originally Posted By: Gary Allan
... That is, no "new" metal is being introduced into the sump, just stuff that was sequestered. ..but whatever the origin, I can't see it having any origin that could justify the term "wear".
My understanding of surface competition between Ep (typ zddp) and say, a calcium sulfonate would point to the possibilty of more wear in a highly stressesd engine when the relative ratio of detergent to EP is high, as when the oil is virgin. Is not this the reasoning used in porpotioning Ep to detergent in race oil and /or break-in oils? see Joe Gibbs.
 
Last edited:
Arco,
Note to self - Proportion is spelled thus. I've been listening to Sprint Cup color commentators too oft of late
wink.gif
 
Last edited:
Originally Posted By: ctrcbob
The owners manual of the last two Renault Laguna's, that I leased while in France state that the oil should be changed every 30,000 km. That is 18,750 miles.

Yes, they use "real" full synthetics in Europe.


Can I ask what the crankcase capacity on that car was?
 
Originally Posted By: Gary Allan
Quote:
How would that effect engine life?


It won't. The quoted text is dealing with valve deposits in the dry intake of DI engines. So "engine life" isn't the issue, per se~. It's side effects and complications.


Quote:
I still believe aside from possibly killing the cat, something I've never done,,,,yet. I don't see much downside other than wasting some money, and resources.


Agreed. This is a policy issue. 30 million people changing oil @ 3k/3m with SL vs. 30 million changing oil @ 3k/3m with SM. Less cat poisoning.

Quote:
I think the wear metals spoken about are from the fresh oil doing some cleaning of deposits left from the older dirty oil.


I don't know if it would be "cleaning" per se~, but disruption of an older film formation in the seating of the new could spike metals that were entrained in the old formation. That is, no "new" metal is being introduced into the sump, just stuff that was sequestered. ..but whatever the origin, I can't see it having any origin that could justify the term "wear".


Thanks for clearing that up Gary!
01.gif
thumbsup2.gif
 
Status
Not open for further replies.
Back
Top