Every oil change is a partial oil change. They all hold some fluid somewhere. It is just a matter of degree. I've left filters in for another run rather than replacing them as mentioned. For work, I maintain filters in other applications, and leaving them with some loading increases their low-micron filtration capacity. As the filter loads, you lose flow capacity so you either start with a larger filter than needed (which is a tricky subject) or use a filter with a lower micron rating, to begin with. The thicker the filter media the better they load and automotive oil filters are typically just thin paper media. They load, then lose flow, so it probably would be best to have a pressure drop manifold where you could evaluate the filter but that is too much work. Just swap them and I don't see the point of a partial oil drain for the same reason. It is too much work. If I'm under the vehicle it is all coming out.
Down side of partial oil changes?
- Thread starter WobblyElvis
- Start date
- Joined
- Dec 28, 2014
- Messages
- 3,001
Yeah, I'm not a fan of this technique. You're leaving contaminants in that dirty oil and just replenishing some oil - I think it would be ok to say, maybe extend an oil change this way a couple thousand miles (by siphoning out a couple quarts and replenishing it), but not actually bypassing an oil change entirely. IMO.
No harm. Also, no benefit.
If you’re able to extract a quart, why not extract all of it?
If you’re able to extract a quart, why not extract all of it?
Have someone change the oil and filter every spring. Your wasting your time and money 1 quart at a time. IMO
Seems like you answered your own questions
If you can’t or do not want to do a proper oil and filter change yourself for any reason then have a friend, family member, or shop do it, and do it correctly.
There’s one right way and many wrong ways to do anything. A partial oil change is not the right way, imho it’s just a waste of new oil.
Z
There’s one right way and many wrong ways to do anything. A partial oil change is not the right way, imho it’s just a waste of new oil.
Z
Why not just do oil change while it's still nice and warm out and before it gets cold? You said you didn't drive much, so one warm day in fall season would do it in case you wanna do it yourself and not to take it to a shop that does oil changes. Just keep adding oil till next fall when you do another oil change or so, as long as you stick with your OCI.
Yet we do it on transmissions ALL the time.
If anyone agrees with this procedure, I humbly suggest you don't listen to them.
Get a MityVac, have someone help you or pay for an annual oil change.
If you lived near me, I would be more than happy to lend a hand. Good luck.
Get a MityVac, have someone help you or pay for an annual oil change.
If you lived near me, I would be more than happy to lend a hand. Good luck.
Yes plenty of reasons not to do it.
A few of the big ones are....
Expunging "Ghost Riders" that accumulate under 10 microns keep accumulating unchecked by the even the best full flow filters.
Reduced oxidative protection.
A tiny amount of oxidated oil - contaminates the new oil very quickly. It takes less than 5 percent oxidized oil mixed with new oil to reduce the oxidation stability of the new oil by more than 90 percent.
Reduced Devrnishing - SVOC results in highly reduced impurity holding capability.
Last edited:
Not the same thing.
Transmissions arent subject to combustion contamination, fuel, or blow by.
- Joined
- Jun 3, 2021
- Messages
- 1,379
Why not take the money you're planning on spending on the Blackstone report and instead use it toward having the oil changed at a shop?
I've known a few guys who just added oil and swapped a filter. Seemed to get away with it too.
Friend of mine had an old Chevy Truck ( 1972) and the dipstick tube was broke off... so he would drive it until the oil pressure light would go red if he was rounding corners....and throw 3 quarts in it... and he sort of kept track of it like that and about the 3rd time he had to add 3 quarts of oil he would throw another filter on it.. he drove it like that for a long time.. Not the preferred maintenance method but it worked for him.
Now there's been times right I had two or three quarts that I found laying around. Especially right when my mom was dealing with chemotherapy and I was over there using her driveway cuz it's much smoother. I had thought the oil analysis kit and it had refrigeration tubing included and I just siphoned out that three or four ounces into that little clear bottle and then dumped it over into an old 5 quart jug. I bet you I had to screw that bottle back onto the softer 40 or 50 times. I really wanted to get underneath there but it's stressed out as my mother had been I just figured I only had another three or four thousand miles to go before my maintenance speeder turn down at 20%. While siphoning I noticed I got a lot of what seem like a water like substance so it was probably gasoline. I know it wasn't the optimal way to exchange fluids, but it's sure better than not changing any of it at all. Of course we already got ours up to operating temperature so I never worried about the oil oxidizing or coagulating. It's better to change some than none but don't make it a constant habit as eventually some of the things down in the sump just need to be removed. It sounds like you might be a candidate for the high performance lubricants engine cleaner 30. Maybe sorry for that around 2 quarts and 1/4 of the engine cleaner and one quart of whatever oil you wanted to use and run it or maybe two or three thousand miles and then have it properly drained from the pan.
Last edited:
You'd be better off buying a cheap oil extractor from Harbor Freight, about 100 bucks. They're pretty decent at getting out nearly as much oil as a normal drain would, and replace nearly all the capacity. Not replacing the filter leaves maybe half a quart give or take depending on filter size. Should change the filter every other or every third change depending on frequency though.
Or you can buy a 12-v electric pump that will do the same thing for 20-something dollars. Besides being cheaper, it has the advantage of requiring less storage space. I've used mine successfully, twice so far, and soon will again.
Whether "getting out nearly as much oil as a normal drain would" is feasible by sucking it out the dipstick tube is highly vehicle-dependent; it works on some, not on others.
Why would you do partial oil changes. Reminds me of the days when I was younger & worked at a no name gas station where we would put that green oil that we had in drums & put in glass bottles to sell to people who were driving smoking clunkers.
I understand that you do not like getting under your vehicle. If you intend keeping your vehicle, I would supply your own oil and filter and have some one change the oil and filter once a year.
I am not a fan of partial oil changes and would never leave an old oil filter on with a partial oil change.
If the engine is at operating temp, then most of the oil will drain out taking some heavy sludge with it thus reducing wear in your engine. Changing all of the oil and filter is money well spent rather than spending money on oil tests.
Similar threads
