I don't like getting under my car and I don't drive as much as I used to so I have simply siphoned a quart out of the sump and added enough to bring it up to full mark for the last year or so. Engine uses a quart per 4,000 miles. Filter is an oversized Fram Ultra so I'm not worried about that. Question is, if this were to continue indefinitely, is there a downside to not ever totally draining the oil?
Down side of partial oil changes?
- Thread starter WobblyElvis
- Start date
I’m not clear on the math here, but ~2 fresh quarts every 4,000 miles doesn’t sound like enough to me.
How much does it hold ? You're refreshing it with (2) quarts so it that's 50% of the capacity, it's probably going to be fine.
Since you're already paying almost $10 for a filter plus ?? for a quart of oil, why not look for a shop that will change the oil and filter for you and allow you to supply the parts ?
Since you're already paying almost $10 for a filter plus ?? for a quart of oil, why not look for a shop that will change the oil and filter for you and allow you to supply the parts ?
Less than ideal but depending on the engine design it may not be relevant. It's not that much different than adding makeup oil to a chronic oil burner which went hundreds of thousands of miles on mobil 1.
The biggest downside in my mind with the newer cars and DI they all to one degree or another suffer from oil dilution. So if you leave a bunch of that oil in the engine you aren't going to be giving it maximum protection.
Just a thought, siphon out the sump leaving the filter in place and add back whatever you siphoned. Do that two or three times depending on the filter quality, total amount siphoned, and driving conditions.
Regardless of what procedure you decide to follow, eventually, you're going to have to change the filter. The problem comes from not knowing the condition of the filter. Apart from it becoming clogged, it could have been damaged. Damaged filters have appeared on BITOG with unsettling frequency.
There are quite a few folks here who only change their filter every other OCI and some, although a lesser number, do it every 3rd OCI.
The downside to your plan is shortened engine life, greater potential for varnish and sludge to build up, and a clogged filter, never mind that it's oversized. And, if you have a direct injection engine, all bets are off. Just curious, what car/engine ae you talking about?
Regardless of what procedure you decide to follow, eventually, you're going to have to change the filter. The problem comes from not knowing the condition of the filter. Apart from it becoming clogged, it could have been damaged. Damaged filters have appeared on BITOG with unsettling frequency.
There are quite a few folks here who only change their filter every other OCI and some, although a lesser number, do it every 3rd OCI.
The downside to your plan is shortened engine life, greater potential for varnish and sludge to build up, and a clogged filter, never mind that it's oversized. And, if you have a direct injection engine, all bets are off. Just curious, what car/engine ae you talking about?
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At some point, it may not even get minimal protection ...
I should clarify this. I do not always siphon out 1 quart. If the vehicle has been drive aprox 3,000 miles, I have removed maybe 2.5 quarts and replaced it with new. If only drive 1,000 and winter is coming [don't want to change oil in the snow] I may only change a single quart to freshen the oil. I try to calculate how much needs to be changed.
When a regular oil n filter change is done, some oil is always left in the engine.
Two problems I can see. Without removing the drain plug, over time some sediment may accumulate in the bottom on the pan.
Second, if the oil is never brought up to completely fresh, the cleaning agents may never be strong enough to remove deposits from the engine.
Just wondering what people think. Later this year I'll probably give it a full change and see what Blackstone finds.
What a bout a continuous use diesel power plant? Is some oil change done with the engine operating?
When a regular oil n filter change is done, some oil is always left in the engine.
Two problems I can see. Without removing the drain plug, over time some sediment may accumulate in the bottom on the pan.
Second, if the oil is never brought up to completely fresh, the cleaning agents may never be strong enough to remove deposits from the engine.
Just wondering what people think. Later this year I'll probably give it a full change and see what Blackstone finds.
What a bout a continuous use diesel power plant? Is some oil change done with the engine operating?
If you have the siphon connected, why not get ALL of the old oil out? What's point of getting just one quart out?
Situation, winter is coming and I'm not in favor of changing my oil in the coming cold and snow. The oil in the engine has few miles on it, but not so few that I think it should stay in there until spring, so some is drained and replaced with new. This way I don't waste relatively good oil, I don't to have jack up the car and lay under it [I'm old] and you would think the oil would be improved enough to make it to a spring oil change.
If this continues and the oil is changed at the usual rate of so many quarts per mile, what are the negative affects on the oil/engine? Why?
If this continues and the oil is changed at the usual rate of so many quarts per mile, what are the negative affects on the oil/engine? Why?
Just syphon (or suction) out as much as you can, less often. That would be less bother, and have the same or better benefit, and same or lower cost. On some---not all--- engines, you can suck out just as much you can get out by removing the drain plug.
I think it's a bad plan for motor oil. You're only diluting the total of ~5 total quarts, with 1 fresh quart. If you do the complex math, you're going to have a lot of really really old oil in the engine after 10s of thousands of miles.
This might work in a transmission that has a 75,000 mile change interval, if you do this method every 10k miles or similar. But in an engine just replacing 20% of the oil every 4000 miles is not going to be sufficient.
Plus how are you changing the filter? Unwise to leave a filter on for 10s of thousands of miles or long time intervals.
One strategy might be a Mityvac to suction out all the oil, and change the filter every other OCI.
Ok but why just replace one quart every month or two instead of replacing all the oil once every 6 or 8 months?
That's a technique used by quite a few BITOGERs and it seems to work well for many folks
You are leaving the majority of dirty, worn oil in the crankcase. You are accomplishing very little with your methods which I can't understand..
Nextime, only drain a couple of gallons of dirty bathwater out your tub then replenish with new before taking a dunk. Same principle.
We don't know the engine, the oil you are using or your typical drive time and frequency. So it's wild guess as to how that practice will work.
You might be better served with an occasion oci at a local shop.
You might be better served with an occasion oci at a local shop.
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