View Poll Results: Have you experienced the Carbon buildup issue on the IS250?
Yes. I got the service done under warranty one or more times
44
43.56%
No. Never had this issue. Car runs like a sewing machine.
34
33.66%
Carbon buildup? What is that? Is Al Gore linked to this?
23
22.77%
Voters: 101. You may not vote on this poll
IS250 Carbon buildup Poll
10-04-10, 03:09 PM
#1
Lexus Champion
Thread Starter
IS250 Carbon buildup Poll
Well I searched and the mother of all carbon buildup thread does not even have the poll to show how many people have this problem. So here it is...
10-04-10, 03:35 PM
#2
Lexus Champion
Thread Starter
I was in discussions with my friends in OZ who also run Direct Injection engines on the Mazdaspeed engines and they have reached this conclusion to avoid carbon buildup.
Do not change your oil every 3k or 5K. Go synthetic and change it every 10K.
Friends from Down Under talking about carbon buildup
Do not change your oil every 3k or 5K. Go synthetic and change it every 10K.
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.
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.
Last edited by chikoo; 10-04-10 at 08:01 PM.
10-05-10, 08:51 AM
#6
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I was in discussions with my friends in OZ who also run Direct Injection engines on the Mazdaspeed engines and they have reached this conclusion to avoid carbon buildup.
Do not change your oil every 3k or 5K. Go synthetic and change it every 10K.
Friends from Down Under talking about carbon buildup
Do not change your oil every 3k or 5K. Go synthetic and change it every 10K.
Friends from Down Under talking about carbon buildup
10-05-10, 09:32 AM
#7
All of the above assumes normal driving though... if you make a lot of short trips and/or idle excessively you'd want to change it a lot more often (and probably don't need to spend $ on synthetic as a result).
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10-05-10, 03:30 PM
#12
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Based on the UOAs I've seen from the 2IS that's still a bit too often... on dino oil 7500 miles (about 12,000 km) is quite safe and several have seen no issues with 10k dino changes, and on a good synthetic there'd be no reason to change any more often than 1/yr up to at least 15-20k miles (25-30k km).
All of the above assumes normal driving though... if you make a lot of short trips and/or idle excessively you'd want to change it a lot more often (and probably don't need to spend $ on synthetic as a result).
All of the above assumes normal driving though... if you make a lot of short trips and/or idle excessively you'd want to change it a lot more often (and probably don't need to spend $ on synthetic as a result).
Also, I'll probably just stick to the Lexus recommended maintenance schedule, at least until the warranty wears out just in case they try to deny me repair service for not following it.
10-05-10, 08:09 PM
#14
Lexus Champion
Thread Starter
How about ignition coils or premature failure of sparkplugs?
Tnx.
10-05-10, 08:14 PM
#15
Lexus Champion
Thread Starter
You guys may be correct. I'm just merely pointing out that the article chikoo posted was in kilometers.
Also, I'll probably just stick to the Lexus recommended maintenance schedule, at least until the warranty wears out just in case they try to deny me repair service for not following it.
Also, I'll probably just stick to the Lexus recommended maintenance schedule, at least until the warranty wears out just in case they try to deny me repair service for not following it.
Regarding oil change schedule following owners manual is a very good practice. I have mot seen one which recommends 3k oil change
My other car is recommended 7.5k on dino under normal usage. Hence i went 10k using symthetic!