Shorter OCI as engine gets older?

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The Critic

The Critic

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Last night, I did an oil change on my 2011 Prius - which just turned 90k.

The car calls for 10k intervals on 0w-20 synthetic.

Early on its life, the oil was still fairly clean towards the end of the 10k intervals.

During yesterday's oil change, it had only been 8500 miles and the oil was extremely filthy. I do not recall seeing it this dirty before.

One thought is that the super dirty oil is due to an increased amount of blow-by that is caused by the engine's age/mileage. I was once told that as engines get older, the ring seal deteriorates and more blow-by is common.

Given the mileage on this engine, should I consider a shorter interval due to the increased amount of blow-by? Does anyone else practice a shorter oil change interval after a certain point?

Thanks
 
Have the cylinder compression tested and find out.

Did you use the same oil as before? And some pictures would help to understand your definition of "filthy".
 
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There are some UOAs in that forum of very mature engines.
Most don't show evidence of excessive blow-by.
You also know that 90K is a long way from being old.
 
I doubt that I have excessive blow-by, but I do wonder if there's an increased amount of blow-by compared to new.

Without a baseline, the info obtained from a UOA would be meaningless...unfortunately.

And 90k is fairly high mileage - 150 to 200k is considered a typical lifespan by industry standards. BITOGers may have personal experiences that differ, but industry guidelines exist for a reason -- and must always be considered.
 
I have been doing 10K OCIs with engines up to 354K with nary a problem. I know others doing 15K OCIs with M1 EP with close to 200K. No problems. I also don't do UOAs and ignore industry guidlines. Works well for me. Just sayin.
 
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Originally Posted By: The Critic
I doubt that I have excessive blow-by, but I do wonder if there's an increased amount of blow-by compared to new.

Without a baseline, the info obtained from a UOA would be meaningless...unfortunately.

And 90k is fairly high mileage - 150 to 200k is considered a typical lifespan by industry standards. BITOGers may have personal experiences that differ, but industry guidelines exist for a reason -- and must always be considered.

What? With over 17000 posts I would think you would learn by now.
 
Originally Posted By: ARB1977
Originally Posted By: The Critic
I doubt that I have excessive blow-by, but I do wonder if there's an increased amount of blow-by compared to new.

Without a baseline, the info obtained from a UOA would be meaningless...unfortunately.

And 90k is fairly high mileage - 150 to 200k is considered a typical lifespan by industry standards. BITOGers may have personal experiences that differ, but industry guidelines exist for a reason -- and must always be considered.

What? With over 17000 posts I would think you would learn by now.


So what? I may have been on this site for a while, but I do not agree with a lot of the opinions on this site. Everyone is going to have their own interpretation of "high mileage" or "works like new." I am going to by generally accepted industry guidelines on the service life of a vehicle -- which is generally 150 to 200k for passenger cars. So by that definition, the 90k on my car is definitely higher mileage.
 
I'm struggling with the same issue on my 02 Suzuki Aerio SX. Last oil change at 162,000, the oil was looking pretty nasty. I've been diligent about changing it at 7.5K per the manual. Always used name brand oil. Bought the car brand new so I now it's owner pretty well. Up till this oil change it's had only Suzuki oil filters it's whole life.

So do I freak out and start changing at 5K or just chill at change at 7.5K.
 
I've noticed the same thing with my Cobalt, which I've had since new. It has 85,000 miles on it, and the oil now is pitch-black when I change it. When it was young it was definitely more of a dark amber. I've always followed the OLM (7000 - 9000mi OCI).
 
My Dad was always a big believer for shortening the OCI as a vehicle aged for the very reasons you mentioned. I can remember when I was in High School, (late 70's), he changed his oil every 5,000 miles on newer vehicles. As the vehicle aged, he dropped that to every 3,000 for cars and 2,000 miles for trucks, (reason being trucks hauled heavy loads, worked in dirtier conditions, were lower geared and thus, higher RPM at given speed, etc.) Worked well for him.

I'm sure others will weigh in with opinions and experience, but one question to consider is peace of mind. If it makes you happy and you feel you're extending the life of your automobile, then drop those OCI down to a lower level.
 
90k is not really "getting older". If the car was 15 years old, or had 200k, then I would *maybe* consider adjusting if UOAs indicated changes.
 
Originally Posted By: Quest
UOA will determine if you can maintain/stretch/lessen the OCI.

Guessing game will not tell you anything.

Q.


I do not think a UOA is the appropriate tool for determining oil change intervals. We do not know the condemnation limits for each engine, nor is a single sample sufficient enough to determine the appropriate service interval.
 
Sure, they are, Critic. We may not know all the condemnation points for each engine, but look at it reasonably. There's little chance that a Prius is going to shed enough iron or create enough soot or accumulate enough insolubles in a 9,000 mile OCI to reach any conceivable condemnation limits. And no, one sample is not as valuable as trended analysis. However, if TBN is still 5 after 9,000 miles after even just one test, I'd suggest that the OCI would be well within the ballpark. It's a little different if one is trying to squeeze every mile out of the oil, obviously.

To your original question, sometimes I have shortened OCIs as the engine gets older. The old F-150 used to dilute the fuel ridiculously and got progressively worse. Obviously, in that case, shortening things up helped.
 
Yes, engines DO wear and will allow more blow by than when it rolled of the lot for the first time. So shortening your OCI does make since, by how much? No one could tell you. IMO 10K is to long anyway, too long if you want your engine to hit 200,000 miles or more anyway. If you want your car to go the distance, I would change it every 5k +/-.
 
Originally Posted By: gregk24
Yes, engines DO wear and will allow more blow by than when it rolled of the lot for the first time. So shortening your OCI does make since, by how much? No one could tell you. IMO 10K is to long anyway, too long if you want your engine to hit 200,000 miles or more anyway. If you want your car to go the distance, I would change it every 5k +/-.



Truly absurd.


The only vehicle I own that doesn't have 200k is my charger and I'm running 10k intervals on everything from my fleet of work vans to my personal vehicles.
How long have you been here?
Haven't you learned that wear actually DECREASES as miles rack up on oil?
Any my engines are spotless inside.

Wanna try again or are you so stuck in that way of thinking you simply aren't able to learn anything new?
 
I think dirt, for lack of a better term, slowly accumulates in an engine, not matter how well it is maintained. Some engines more than others, but eventually it builds up. I'm not talking about any crazy accumulations, just slow and steady. Then as the engine ages, the oil becomes dirtier faster as a result. Add to that a little more fuel dilution as injectors wear [?], maybe some blow-by and Critic's observations make a lot of sense. A shorter OCI might be a good idea. Flame suit on.
 
As long as the engine is clean (no sludge) keep the manufacturer's OCI's.

Heck... I do 20K miles on an oversized oil filter on our Hondas, zero sludge.
 
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