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Owner Oil Changes

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No Muss, No Fuss

A strong case to change your own oil can be made. You certainly can save a fair amount of money, especially if you get your oil by the case, but more importantly, it puts you in touch with your engine’s lifeblood. You can see how it looks and feels from change to change; smell any burned odors, feel it between your fingers for any grit.

People initially think that one cannot get such a sensitive feeling for oil condition to the touch, but it’s absolutely true that you can, especially when the oil starts to get into the blow-by mode, and the burned smell is hard to miss as well.

You can actually tell how the multigrade feels compared to the straight weight just with the sensitivity of your fingers if you do it often enough, although that is not a particularly needed skill. What is needed is being able to tell when any grit or lack of a slick feeling to the oil is starting to build. If checked regularly you can absolutely tell as oil looses it’s new feel. Of course 25 to 30 hour oil changes pretty much obviate such an intimacy with your oil and the feel to the touch, but not the smell, a real indicator of blow-by.

A simple trick is to rub a few drops of used oil between microscope glass slides. If it scratches the slides, (The scratches will be visible to the naked eye), then your oil is going too long between changes, and there is debris in the oil that is adversely affecting your bearings, which are very soft material.

What happens is this hard material in the oil imbeds itself in the babbitt material of the bearings and acts like sandpaper on the crank journals. Replacing a crank at the next overhaul because you let the oil change intervals go too long is something you do not want to happen.

Also, you really want to do a thorough job, and catch a sample to send out for analysis at least every other change, if not every change, and log the results or use the oil analysis site software to track your oil results. Some oil analysis sites have some sort of individualized data storage system you can access from the Internet. 

Most critical are how much oil you are using between changes, providing you maintain the same flying hours and conditions. And this is an important distinction to make. If it’s all cross country one time and all in the pattern on another occasion, then the likelihood of a noticeable difference in usage is likely going to be there without necessarily a problem, since the conditions were different, and many older engines will vary their oil usage significantly with such engine use changes.

For example, in our Bonanza we noted a 50 percent reduction in oil usage when going cross country, compared to just primarily doing pattern work. That was 8 hours to the quart for long cross countries. Take these things into consideration before becoming alarmed about your oil usage.

Such usage is not a sign of an engine in pristine shape, but it’s not necessarily a sign of a top being needed to fix anything, either. We went many hours and years with an IO-520 that had these oil usage traits that never changed. However, if you are only getting a few hours to the quart under any condition, that’s a different story and it needs to be looked into.

Also, save the filter to cut it open and check the filter media for debris. Doing this, you also get to look at the condition of the filter media. We had one owner send us several crushed filter media internal canisters in a row, which was very alarming, and we erroneously initially thought it was defective filters, since he said oil pressure was more or less normal, but it turned out he was using the wrong filter after he had the engine overhauled—adding a spin-on filter adapter. He apparently missed the abnormal pressure readings or they were very transitory or the oil pressure gauge was wrong.

In most Continentals the bypass spring is in the filter and on most Lycomings the bypass spring is in the engine oil filter mounting adapter. You certainly do not want to have both bypass springs—it’s one or the other. In short, this owner had no idea there were such internal design differences in oil filters, which was causing all sorts of oil pressure and debris problems. We can only assume that he failed to read the oil filter instructions, or they were not furnished by the overhauler who installed the adapter, because they are there on the instructions with such a warning—we checked them on the Net.

When he overhauled the engine and added a spin-on filter he also made starts in moderately cold weather. The filter was for a Lycoming and had no bypass spring in it  (remember, he had a Continental). Such starts can also cause an oil hose failure, especially on an older, marginal oil hose.

Yin and Yang

Oil analysis and filter cutting are two distinctly complimentary procedures looking for different types of problems. It also gives you a chance to look for leaks or any other untoward conditions that can head off a bigger problem if let go.

First, let’s establish the legalities here. Part 43, Appendix A of the FARs deals with preventative maintenance. Of the 33 or so listed preventative maintenance tasks, items 6 and 23 permit aircraft owners who possess at least a private pilot’s certificate or higher to change the oil and the filter (or to service the oil screen) in a certificated aircraft of which they are the owner.

The writing is a bit convoluted on the specific type of filter e.g. spin-on vs screen, but no one will be cited for changing their own oil. It is not legal to change the oil in your friend’s C-150—you must be the owner (or part owner).

The quality of the work must be up to same standards as would be accomplished by a certificated mechanic— i.e. FAA approved standards using FAA/PMA approved materials. In short, if you have never changed the oil in your plane, by all means have a mechanic take you through the steps the first time.

You also have the responsibility of returning the aircraft to service by placing your name, pilot certificate number and date of the preventative maintenance. Homebuilders have no such constraints other than preventative maintenance may be done by the builder, current owner or a certified mechanic. That said, the FAA model is a good one.

Minimize the Mess

Owners who have easily accessible filters and oil drain plugs for oil catch buckets may be wondering what the problem is. Those who own aircraft with arcane, inverted filter locations that hold the oil when the engine is shut down, or with devilishly located oil drain plugs will appreciate the mess factor. 

I’m here to tell you that it’s possible with a few tricks and possibly an accessory or two that you can greatly reduce the mess factor. Most of the accessories are relatively cheap, such as a device to pierce and drain the oil filter before removal. One high-cost exception is a remote-mount oil filter setup, which can cost $1500 installed. This should only be a consideration if it’s just about impossible to get to an adapter setup attached directly to the engine.

You make things much easier and more effective by adding a filter adapter right to the engine to replace the existing screen. Of the bolt-on adapters, the factory model is the most expensive and least flexible, since it is straight. Aftermarket adapters are available with 45 and 90 degree bends that may make filter access a virtual breeze.

Additionally, with a filter you enjoy going from 25 to 50 hour oil change intervals, (or 4 months) and the comfort of superior oil filtering for potentially longer engine life. These adapters may be had for $200-400 plus easy installation by a mechanic, or yourself under supervision. These adapters are available through virtually all the aircraft parts catalogs such as Aircraft Spruce.

Low Cost Accoutrements

Next on the list of making things easy and cleaner is the use of an oil drain valve (also available from Spruce). This time and mess saver screws into the oil drain hole and is designed and FAA approved to be just as safe as the oil drain plug it replaces. (Non FAA-approved models are available, too.)

Warning, be sure to check both your aircraft documentation as well as the aircraft application data on the oil quick drain. While the quick drain valves are quite short, in rare instances they can interfere with gear retraction of certain aircraft such as in some Piper Arrows. (There are now low profile units for Arrows, so be sure to check the separate catalog listing).

Once you have the quick drain installed you are free of much of the oil draining mess. For the next oil change, secure three feet of inexpensive flexible vinyl or rubber tubing to go over the drain lip (snug fit or it can slip off at an inopportune time) and thread the vinyl tube through the bottom of the engine cowl. E.g. through the cowl flap opening to a waiting five-gallon bucket that you have purchased expressly for this task. Be sure you have a routine for beginning the oil flow or the first several ounces of oil will spill into the engine compartment. 

Be sure the bucket has a snap-on, secure lid to make oil transport to the recycler easy and clean. These are readily available at hardware and paint stores for around $5.00. It also enables you to keep your hands on the oil so if you should find something in the filter you can run the rest of the oil through for further checks of debris since quantity of metal in the oil makes a difference between grounding a plane or not, though most filters will catch most fine metal. Screens have a larger mesh.

Don’t forget to wait until the drain tube is in the bucket before turning on the oil flow. By the way, never drain cold oil—it does not get all the junk out of the engine nearly as well as hot oil does from a trip around the pattern. 

Finally, let the vinyl tube sit attached a while after the drain valve has been closed to give the residual oil in the tube time to drain into the bucket.

We recommend a dedicated bucket, so that in the event that you find debris in the filter you may want to drain the entire contents of the sump through a fine funnel filter to another bucket for signs of any other contaminants.

For those who have an oil filter that cannot be removed without a mess—even a plastic bag around the filter fails—then a device is available from Aircraft Spruce that has a plastic hose attached to the device that punctures the filter to allow a controlled drain of the filter before removal. Most engines should not need such a device, but be aware there is one available. The gasket at the base of the filter should stick to the removed filter. Be sure to check so that it doesn’t stay behind on the filter mount.

Completed Staff Work

If you want to do a more thorough job, make a mid-stream catch of an oil sample, as well as drain the oil through a funnel suspended to the inside of the oil catch bucket. Get a funnel that has a fine mesh screen molded into it, so as to catch any bits suspended in the oil, rather than fishing through or draining the bucket through a screen after the fact. It’s all part of a thorough, systematic job to get the maximum information that the oil change can tell you with minimum work.

You can also use that same funnel (after you clean it or use a second dedicated funnel) to put new oil into the engine through the typically small, sometimes hard to reach oil/dipstick tube. Besides avoiding spilling oil onto the engine, the screen serves to avoid the not uncommon mistake of dropping something into the engine such as oil bottle caps or the “cap keeper,” the little plastic devil that makes removing the cap so difficult.

If we seem obsessive on care and cleanliness it’s because we have seen so many minor incursions of dirt ruin an engine over not too many hours. You just can’t be too clean or careful. Things like keeping the funnel clean between changes and not exposed to atmospheric or hangar dirt and dust to build up on an oily, dust attractive surface.

Before use, look the funnel insides over for any type of contaminant and clean it out if you find anything at all. It’s a methodical process of keeping everything clean that the oil will touch before it enters your engine sump.

Based on complaints of low oil pressure of unknown causes we once tore the pan off an IO-520 and found five plastic oil cap “keepers” in the sump. We had found the cause—five plastic “keepers” sticking to the oil sump pickup screen.

Along the vein of minimal mess, drop that old oil filter into the funnel inside the bucket so it can drain for several hours before you cut the filter open. (After an initial drain interval, you can transfer the filter to a one pound coffee can with a plastic lid if you are in a hurry to get rid of the oil.) Never cut open a freshly removed filter unless you want an unholy mess of oil everywhere.

Be sure to not let the engine sit without a new filter for any lengthy period of time, as it is possible for some engines to loose their prime. This usually means a mechanic will need to help you to get trapped air out of the oil system so the oil will circulate properly and you will have oil pressure at startup. If you don’t have oil pressure after several seconds post-start, shut it down and seek a mechanic’s help—you probably lost prime. Most engines are not overly sensitive to this potential problem.

Be sure to not let the engine sit without a new filter for any lengthy period of time, as it is possible for some engines to loose their prime. This usually means a mechanic will need to help you to get trapped air out of the oil system so the oil will circulate properly and you will have oil pressure at startup. If you don’t have oil pressure after several seconds post-start, shut it down and seek a mechanic’s help—you probably lost prime. Most engines are not overly sensitive to this potential problem.

No Cost Helpers 

Sometimes simply wrapping a half—or gallon sized plastic bag around the filter after it has been loosened just a bit to allow hand removal can significantly lessen the filter removal mess. It takes a bit of a deft hand, but the plastic bag can catch most drips with a bit of practice. Judicious placement of shop rags is another simple preventative step. Just remember to remove them before firing up that engine!

For nominal costs there are special plastic filler devices that make pouring in the oil much less messy. The first time that you spill a half quart of oil on the engine you will wish that you had bought one. Some Cessnas can be easy to make a mess with a tight door opening and a short filler neck.

Making the Cut

Cutting open an oil filter should be considered mandatory for the potential lifesaving information it may someday give you if you find metal or other debris. Cutting a freshly removed filter can be a truly messy affair, however, so wait for it to drain into the funnel screen first for at least an hour. Overnight is even better.

Also, use a purpose-made filter cutter to save your fingers, and avoid contamination of the filter contents. It allows you do the filter cut in under 10 seconds. A seasoned mechanic can help you diagnose any findings.

Generally you will find nothing—and that’s a good thing. If you do find anything, especially any metal, bring it to the attention of a trusted A&P who will have a number of questions, and the plane may need to be grounded until the cause is found. If under warranty contact the factory or overhauler as well.

Dedicated Tools 

You should use a torque wrench if possible but the hand 3/4 turn approach works, too. We don’t think the torque wrench dedicated exclusively to the filter is needed, since you should already have a torque wrench for many other preventative maintenance tasks you do.

Be sure that you practice your safety wiring a bit so that you can do it properly. Be sure to secure it to the proper place since the engine moves when running and will snap the safety wire if improperly secured.

Loose Ends

Unless you are going on a cross-country, most engines do not need a full sump. The first quart is rapidly used/lost in many older engines. Flying a quart low is perfectly fine, and will not affect oil temperature. We tested for this problem even at minimum sump volumes, which vary by engine, but can be as low as 2 quarts on an 8 quart engine. If you are at a low sump volume then run at a low rpm to minimize demands on the oil. Don’t start out knowing the sump is that low either.

Be sure any required safety wire has been replaced e.g. filter or oil drain plug if used and is attached properly.

Always ground check the engine for leaks or anything left behind in the engine before flying. Make the required log entries; and make the next flight local, if possible, so you can double-check your work and assure the filter works properly.

A version of this article appeared in the August 2013 issue of Light Plane Maintenance magazine.

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