Oil consumption and the end of an OCI

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Honestly this is the first time i have seen it...also during the past 2 months the car had problems with a few sensors including the throttle body, idk if fuel dilution is an issuse.
UOA out of the question because its not possible in my country
 
I've seen oil consumption increase slightly at the end of an OCI, not real severe though. Figured it's just due to oil breakdown and shearing thinner if that's a thing.
 
Originally Posted By: Garak
I don't know about "sudden," but my experience has always been with consumption ramping up towards the end of the OCI, in the vehicles that consume oil.


I have seen this before..
 
Originally Posted By: Nissan101
Honestly this is the first time i have seen it...also during the past 2 months the car had problems with a few sensors including the throttle body, idk if fuel dilution is an issuse.
UOA out of the question because its not possible in my country

Then consider a Blotter Spot Test ..
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Well i got the oil changed
Within 2 weeks i will recheck the level to see if a there is a developing consumption problem or if the oil was bad(contaminated, fuel dilution etc).
 
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Originally Posted By: Garak
I don't know about "sudden," but my experience has always been with consumption ramping up towards the end of the OCI, in the vehicles that consume oil.


+1.

and i don't think it's the usual oil thinning explanation. when oil (5W30) consumption accelerated in my son's ion toward the second end of 6000 mile OCI, i topped with 15W40 (used 2 qts IIRC) and it didn't slow it down. I just changed the oil and used 15W40 this time.
 
Yes, it was fairly common with cabs that burned oil, and my oil burning LTD. After a fresh oil change, things would be good for a while, then ramp up. And yes, topping up didn't help, either, other than the fact you do have to top up.
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i have a theory on this but no way to prove it. when i had oil burning corolla (it started suddenly at 75,000 miles, but the initial burn rate was slow), i noticed that piston MMO soaks would stop oil burning for ~3000 miles (regular oil) or ~5000 miles (synthetic) before oil burn came back. I ended up doing those soaks every OCI to be oil burn free with synthetic oils.

so, my theory is, when piston oil holes plug up (with oil age and/or abuse), fresh oil (or better oil flush or piston soak) will clean the oil ring groove, but the rings will stuck up with the aging oil again if there is poor oil circulation (ie the plugged up oil holes, that part is irreversible).
 
Originally Posted By: Garak
I don't know about "sudden," but my experience has always been with consumption ramping up towards the end of the OCI, in the vehicles that consume oil.


Yup. It's an indicator of time to change ...
 
Originally Posted By: friendly_jacek
so, my theory is, when piston oil holes plug up (with oil age and/or abuse), fresh oil (or better oil flush or piston soak) will clean the oil ring groove, but the rings will stuck up with the aging oil again if there is poor oil circulation (ie the plugged up oil holes, that part is irreversible).

That may well be true. We just added, and of course, we could always expect a few differences in causes of consumption with different vehicles. Consumption is a royal pain in the behind.
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BrocLuno: I had some similar cases with the old F-150, but that wasn't consumption so much, as the oil getting diluted to heck near the end of the OCI and giving me a low oil pressure light at hot idle. That's where MaxLife and HDEO came in.
 
How long of intervals?

Oil can thin out with use.... then eventually thicken if used too long.

On my work truck the oil would thin out usually around 6k miles. I could tell by some oil usage and the gauge (chevy). I did an analysis and everything was fine except the oil sheared down some. Switched to synthetic the last couple times and it has stayed up in grade. Last oil run was 10,000 miles with a lot of highway and medium towing. Did an analysis and all was good.
 
Originally Posted By: cmlind
How long of intervals?

Oil can thin out with use.... then eventually thicken if used too long.

On my work truck the oil would thin out usually around 6k miles. I could tell by some oil usage and the gauge (chevy). I did an analysis and everything was fine except the oil sheared down some. Switched to synthetic the last couple times and it has stayed up in grade. Last oil run was 10,000 miles with a lot of highway and medium towing. Did an analysis and all was good.

Interesting observation.
Never thought about a sheared oil could contribute to oil consumption ...... makes sense to me.
Mind sharing oil viscosity grade in use that shears ? ...... including synthetic's .
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The oil consumption with time/miles was an age old problem before modern synthetics. Was that way since I was a kid in the 1950's. That's one of the main reasons for the old 3,000 mile OCI. And we noticed that vehicles with fresh oil did better on SMOG Checks. So our family would always have an oil change before going to the SMOG Station for a test.

You can get away longer now. But not with cheap oil...
 
One time I ran an intverval of MC 5w20 syn-blend. The oil level was fine at the 7k mark. At 7500 miles it was down either a half or full quart, can't remember at the moment how much.
 
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