Using oil late in OCI

[mannyhs]

I have a 2.7L V6 in my Hyundai and so far the engine hasn't used any oil between oil changes which are normally done around 7-8,000 kms with either conventional or semi-synthetic. The car sees about 60% highway and 40% city.

I decided to run synthetic this winter and stretch the OCI out to 12-14,000 kms and then do a UOA for curiosity's sake. It's an old engine, I know, but I thought it would be interesting to find out what came back on the analysis.

The car has 210,000 kms on it and, as I say, didn't use any oil between changes. I'm currently at 11,000kms on this change and the last time I checked the oil about 2-3 weeks ago, the oil level hadn't move from full. When I check the oil today after driving 4 hours to visit family for Easter, the oil was down by about a 1/3 of quart.

I know it is common for engines to consume oil over the OCI and 1/3 of a quart isn't that much (especially for 11,000 kms) but I'm just curious why it has done it all of a sudden.

Does the oil's volatility increase with longer use? Another explanation for this?

 

[Shannow]

Not sure, but my Nissan usually uses nearly a litre at 7,000km into a 10,000km OIC (did it at 5,000 this OCI)

 

[Colt45ws]

I have noticed this too when I let OCI go out. All of a sudden I start losing oil. 1qt suddenly disappears in 1000 miles.
I take it as a sign to change it and so I do at my earliest convenience.

 

[Skid]

4 hour drive. Probably burned up the fuel dilution in your old oil.

 

[Pontual]

Long highway miles, equals warm engine oil operations. That does eat some oil.

 

[Lyman]

Originally Posted By: Skid
4 hour drive. Probably burned up the fuel dilution in your old oil.

This would be my guess also.

 

[BikeWhisperer]

I've owned vehicles that under 90% of my driving never consumed a drop, but a long freeway drive at higher speeds (ie higher sustained RPM's) and pulling some grades along the way would suddenly lose a half quart.

So maybe not unusual at all, not sure it has to do with the longer OCI or not.

 

[simple_gifts]

Originally Posted By: Blkstanger
Originally Posted By: Skid
4 hour drive. Probably burned up the fuel dilution in your old oil.

This would be my guess also.


This situation is actually documented in my Toyota OM.

Quote:

As an example, if a vehicle is used for
repeated short trips, and consumes a nor-
mal amount of oil, the dipstick may not
show any drop in the oil level at all, even
after 1000 km (600 miles) or more. This
is because the oil is gradually becoming
diluted with fuel or moisture, making it
appear that the oil level has not changed.
The diluting ingredients evaporate out
when the vehicle is then driven at high
speeds, as on an express way, making it
appear that oil is excessively consumed
after driving at high speeds.

 

[mannyhs]

Thanks for the responses!

I hadn't considered the long drive ... the car makes short highway trips quite often and I've made this drive to visit family twice already during this oil change.

That's an interesting bit from the Toyota manual ... it makes sense, although I'm not sure why it's gone from no use to 1/3 of a quart just in the last few weeks.

Part of me really wants to top it up but I was planning on getting a TBN reading on the UOA and don't want to skew it!

 

[Pontual]

My Taurus never cosume oil in city driving and ate 1/2 quart in a 500 miles straight trip, with new oil, so not dilution related, just for higher rpm and higher oil temperature, with 10w40 semisyn, not a thin oil also. Back to city driving at lower rpms and no consumption again.

 

[zpinch]

Who cares about skewing the UOA?! If your engine needs some oil, then add some oil when it needs it, as that is the oil your engine is going to be running on. Run the oil out a bit before you do your UOA if you are so concerned.

VI Improvers being used up will allow the oil to have higher volatility, also, dirty oil will allow poorer ring seal and allow more oil into the combustion chamber, as well as allowing more contaminants into the oil, further accelerating the oil degrading process.

 

[mannyhs]

You're right, it wouldn't be the worst thing to have to add oil. I don't have any Amsoil left unfortunately.

 

[4wheeldog]

My old school way of looking at this kind of usage is.....Use the mileage point at which it started using oil as the time to change the oil next time. But I am over conservative about OCI. And none of my current vehicles get OCIs long enough to use any really measurable amount.

The OP has no idea if the oil he has used in the past would have been consumed with the longer interval. The safe thing to do is......Change the oil at the shorter interval. But many consider anything less than 12k miles (18k kilometers) as wasteful.

 

[mannyhs]

Originally Posted By: 4wheeldog
My old school way of looking at this kind of usage is.....Use the mileage point at which it started using oil as the time to change the oil next time. But I am over conservative about OCI. And none of my current vehicles get OCIs long enough to use any really measurable amount.

The OP has no idea if the oil he has used in the past would have been consumed with the longer interval. The safe thing to do is......Change the oil at the shorter interval. But many consider anything less than 12k miles (18k kilometers) as wasteful.


I might top it up and run it another 1-2,000kms. I wanted to try Amsoil and my local parts store only had Signature Series. I don't quite feel like I have gotten my money's worth yet! lol

Although, this winter was extremely cold in eastern Canada. Probably was quite hard on the oil.