Oil Change Management - Partial Changes

[starvin_sgt]

Ok Bobbers, I have a vacuum pump and tank so I can remove fluids in a very convenient way. I have noticed that on many threads wear rates go down with extended OCI’s.

Some of these seem attributable to the quality of filtration but another theory is that the additive package is more aggressive when it is new leading to new oil wearing an engine more than old oil does.

Or put another way the trend in wear is lower for the last percentage of use than the first. So my thought is the idea of partial oil changes. One of the other drivers towards this idea is that the folks using bypass filters with very long OCI’s add make up oil and often have very good UOA’s. So for your consideration:

1) Is the idea of partial changes every 5k on dino or 7k on syn seem like it has merit both for cost and the best chance at lower wear?

2) What percent of oil should be removed

3) Would you consider using a more exotic oil and perhaps additive with this method of oil change management?


Obviously the only reason for this exercise is…well…sheepish grin…I am a nerd about somethings!

 

[LeakySeals]

So..you don't have to go under to replace the filter?

I see what your doing as a "drain and fill" similar to the transmission, coolant, etc. That means cutting back the interval based on the % your getting using the device.

What % of the total are you getting? Have you measured?

 

[starvin_sgt]

Thats the beauty of it, I just suck it up the dipstick tube in any amount I want to

 

[tommygunn]

Beauty of it is it'll never remove any contaminants that settle to the bottom and settle into nooks and crannies, and oil filters wear out and need to be changed, aswell as your method will never change the oil in the oil filter.

Can the Jiffy Lube techniques; they're terrible unless you're in a rush.

 

[LeakySeals]

Originally Posted By: tommygunn
Beauty of it is it'll never remove any contaminants that settle to the bottom and settle into nooks and crannies, and oil filters wear out and need to be changed, aswell as your method will never change the oil in the oil filter.

Can the Jiffy Lube techniques; they're terrible unless you're in a rush.

Your showing your age, its been 20 years since Jiffy Lube tried that (and stopped).

 

[starvin_sgt]

I don't think what I am doing is clear. I use a flexible hose to put it any length down the dip stick tube including way deep down, very little oil escapes the kind of vehicles I have. Of course if you have an odd shaped pan or are not careful you will do a bad job removing the old oil. This is great for auto tranny oil replacment BTW.

The heart of the issue is the idea of partial oil changes any feedback?

 

[tommygunn]

Full oil changes will properly flush out contaminants better then sucking small amounts out, and regular filter changes are always necessary.

You're better off just running a full OCI and replacing the filter, and draining the oil properly, ensuring all contaminants are washed out.

Partial drains might let you extend an OCI slightly; but it will never be cost effective enough without UOA's and careful testing of oils and selecting better filters and seeing if you can stretch is any further with that method.

But unanimously it won't be worth the hassle and you'll get far more contaminants then you'll be able to get out with a siphon.

 

[LckydevL]

I would be concerned about a possible oil filter failure. It is only a $5 to $15 part and not made as good as they can be for a reason. It needs changing and any oil filter can become clogged up.

Otherwise, your experiment seems plausible.

 

[_phil_]

I've read here or elsewhere that cars that burn through significant amounts of oil could almost do without an OC because the constant top-ups effectively replace the oil over time.

Based on that thought I'm doing exactly as you propose. My normal OCI is 15,000km so I reasoned, without knowing, that replacing half the oil near half the interval could only be better than leaving it the full stretch. That replenishing some oil and not all could actually be worse is so counter-intuitive that I'm able to reject it.

BTW I leave the filter the full journey and replace it every full OCI as normal.

 

[skyship]

There is nothing wrong in principle to a partial oil change if you are just trying to top up the additives because the TBN is low, but the rest of the UOA results indicate the oil is still good.
Unless you have a very good reason the oil filter should not be changed before the manufacturers recommended interval, as oil filters work much better when dirty than when they are new. Changing oil or air filters too often is both a waste of money and bad habit in long term engine wear factor terms.
My own diesel has a recommended oil & filter change interval of 20,000 km, but due to severe service considerations I change the oil only at 12,000 km and then do a full oil & filter change 8,000 km later and those figures are designed to allow for the old oil left in the filter.
Sucking oil out of the dipstick would be OK if you do it as soon as the engine is turned off, but the drain plug should be used at the full service interval just in case there is some kind of sludge or debris.

 

[Doog]

Originally Posted By: starvin_sgt

The heart of the issue is the idea of partial oil changes any feedback?

 

[Doog]

Originally Posted By: skyship
Changing oil or air filters too often is both a waste of money and bad habit in long term engine wear factor terms.


LOL

 

[skyship]

Although partial oil changes can work in both engine wear and cost terms, I would stress that you would need to be doing on condition maintenance with regular UOA's to figure out what is happening to the oil quality.
Anyone with a significant oil leak that tops their oil up is in effect doing partial oil changes, but just because your engine uses more oil it does not necessarily mean you can extend the service interval and the oil filter should always be changed at the recommended interval, BUT don't forget that 90% of the debris that passes through a normal full flow oil filter does so in the first 10% of a new filters life, so new oil and air filters are something of an engine killer if you change them too often.
Using additives is a whole different subject and I would avoid them if possible as most are just snake oil and some even cause long term harm and can even cause sludge problems. If in doubt leave them out and buy a better oil.

 

[cp3]

I'm with skyship, I think it could be effective if managed properly. Unfortunatley the added cost of UOAs would likely eat up any cost savings. If cost wasn't a factor in your theory then sure, probably worth a shot just for fun. You didn't mention a filter change interval and if that would be done with a complete drain. I think this could be an important factor in your plan. Obviously leaving it in place too long would not be good but I also feel with the pics posted in the filter section, many filters can go longer than the factory OCI, especially the top end and synthetic filters.
Stictly related to wear though, with the performance of todays oils, I don't know that you would see a big enough improvement for it to be worth while.

1) 5k or 7k partial change on the way to what? A full OCI with filter at 10k or 14k? Or more partials up to what point?

2) I'm not sure how you would determine this. Too much and you will get that new oil wear you are talking about and too little and you might not replenish enough of the spent aditives. Best bet would be to try to figure out based on UOAs at those intervals to get a starting point.

3)Again, more exotic (expensive) oils will take away from any cost benefit to doing this. IF it were feasable with a regular OTC oil, it might be worth investigating a more exotic brand that could allow you to extend intervals some more.


Jiffy-Lybe techniques? Vac oil changes are very popular, especially for those with cartridge filters, like some high-end German sedans....

Not sure how the changeing filters too often comments are crazy either. That a filter gets more efficient with use is not a new idea.

 

[skyship]

Oddly enough the quick lube places in the EU don't use the pump out method, that seems to be a US bad habit. It works well with some engines, but with others you can't get the intake pipe exactly in place at the bottom of the sump and tend to miss some old oil as a result.