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Vacuuming out oil when not changing filter?

RVphil

Member
I'm not a fan of pulling cowls on my 7A just to change oil. Despite the fact that not all of the oil is scavenged if vacuuming out the sump, what other downsides are there with the procedure?
 
Pulling the cowl allows the opportunity to inspect the FWF area. Could save your life!

Most definitely, and I've done some minor maintenance during other oil changes but nothing that could compromise airworthiness if deferred (e.g. EGT probes).
 
I would NEVER consider changing the oil and not the filter. Why would you want to run new, clean oil through a dirty filter.
 
For clarification, the IO-390 is on a 25hr oil change and 50hr oil/filter change regimen. The 25 hour oil change procedure is what the sump vacuum question is about. Engine has never made metal and oil analysis is taken @50hr when filter is changed.
 
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For clarification, the IO-390 is on a 25hr oil change and 50hr oil/filter change regimen. The 25 hour oil change procedure is what the sump vacuum question is about. Engine has never made metal and oil analysis is taken @50hr when filter is changed.

If you are absolutely adverse to pulling the cowl for the intermediate oil change you might consider adding a small service access door under the oil sump drain. A hose could be connected to a quick-drain fitting.

But I always pull the cowl for oil changes or any minor issues that pop up between changes.
 
Well - I am going to support RVphil !

Well done for thinking about regular oil changes, best and cheapest maintenance you can do.

If you replace the oil at 25 hours/6 months and change the oil and filter on an annual/50 hour basis - no problem.

The filter will not be contaminated or diseased by being left on, the oil is doing the work, the filter is removing rocks, nuts, etc :D
 
vacuum

I have never looked inside my "cold air" sump to see how the oil flows out, and compared it with how much could be picked up by a vacuum. I use the vacuum method to change my car oil since it's so much work to get under there and remove everything needed to get to the drain. The filter is pretty easy and is reachable from the top.

I think I will try the vacuum method and see if anything else comes out of the drain after finishing, just out of curiosity.

I have the anti splat aero magnetic drain, so I will be looking for nasties there on each oil change.

rs=w:600,h:600
 
I have never looked inside my "cold air" sump to see how the oil flows out, and compared it with how much could be picked up by a vacuum

There are a few YouTube vids showing the vacuum method (on cars mind you) removes more oil/trans fluid than the standard drain. Interesting if nothing else... but no idea how it would do with the geometry of our engines, or even if the YouTube folks are really showing impartial tests
 
I'm sure there are videos out there on the procedure. I must give credit to the sump vacuuming idea to a 10+ year old post on here while researching engine oil options. Topic wasn't discussed at length, however.
 
I would NEVER consider changing the oil and not the filter. Why would you want to run new, clean oil through a dirty filter.
^^^^^AMEN^^^^^

Besides, if you have 7qt in your engine and it burns 1qt every 10hrs, then at the 25hr point you will have already replaced 2.5qt with new oil. :confused:
 
^^^^^AMEN^^^^^

Besides, if you have 7qt in your engine and it burns 1qt every 10hrs, then at the 25hr point you will have already replaced 2.5qt with new oil. :confused:
I can see there are situation that one would want to change the oil but not the oil filter. Lets say that you have flown only 4-5 hours in the last four months and it is time to change the oil due to the calendar time. Is it that critical to change the filter? Changing oil is easy but the oil filter in some cases due to access could be more time consuming. The oil filter is about 4 hours of flying gas and another filter to the land field.

Having said that, it has only been one time for me to change the oil and not the oil filter.
 
I'm not a fan of pulling cowls on my 7A just to change oil. Despite the fact that not all of the oil is scavenged if vacuuming out the sump, what other downsides are there with the procedure?

From the basics of the engine, a non-issue to vac out the oil and not replace the filter per the manual. As long as the engine was just run and the oil retains solids in suspension. The oil filter actually gets a little more efficient as it collects debris anyway. The downside of the filter capacity being used is it will be closer to opening the bypass when cold. If you preheat the oil 80F every flight then that would be a lower probability.

As mentioned, the downside is not seeing a new oil leak/weep or other issue with the cowl off. Something more likely than an engine issue [IMO]. OTOH, if 50 hrs is typical, then it seems to be a wash.

From an academic standpoint, a series of oil analyses might be in order to see how the numbers are tracking with the procedure, considering that 25 hrs is being recommended, what is the oil doing that it needs this change. The ISO particle count, and oxidation would be the parameters of interest. Particle count as the bearings may have less film thickness and oxidation in case some internal temperatures seen by the oil are higher.
 
I'll send in oil samples from the vacuum outs for a while to see what changes. Engine oil is analyzed at every 50 hour oil/filter change. Insolubles generally range from .2 to .4 according to Blackstone. Oil is always drained hot.
 
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