If you take your high-speed bug smasher to most shops for an oil change, you’ll pay full retail for the oil and filters plus somewhere between 1-1.5 hours of labor at standard shop rates. If you drive a double-breasted bug smasher the costs double. In fact, it may be more than double since many shops have a higher hourly rate for twins.

Since FAR 43 A(c) allows you to change your own oil, why not buy a case or two at wholesale and do it yourself on a Saturday afternoon? It’s easy to do mentally, not very demanding physically, and will give you an opportunity to impress your significant other with how you’re the master of your fate and a legend in your own time.

Well, okay — no one will care that you know how to change your own oil, but you’ll save money and it really isn’t difficult to do.

Single-grade or multi-grade?

I personally don’t like multi-grade oil. The reason is simple: I tried it twice over the years and both times the engine developed leaks at the case seam.

Now, I know this is anecdotal information and therefore suspect. I also know that those who live in the frozen north and don’t fly enough to change grades based on the season will argue that multi-grade is the only way to go. And I also know that lab studies do not support any allegation that the chemistry of multi-grade oil is sufficiently different that its molecules can find ways to escape their crankcase prison more efficiently than their single-grade brothers.

All I know is I tried it twice, once with a Lycoming IO-540 motor and once with a Continental IO-470 motor. Both started leaking whereas they previously didn’t leak. I don’t plan to try it again.

My current ride has a Continental TSIO-360 EB on one wing and an LTSIO-360 EB on the other wing and I use AeroShell W100 Plus exclusively except in the winter when I drop back a grade since it does get cold in Kentucky in January and February.

Ultimately, the choice is yours. The reason I use AeroShell W100 Plus is because it was developed for Lycoming engines to help with some unpleasantness involving early failures of rather important moving parts, but its adhesion properties work just as well in a TCM engine.

All oils approved for use in aircraft engines are safe — meaning they normally don’t cause spontaneous disassembly of anything important. Some have added properties that are desirable, so you’ll have to match your kind of flying to the variety of products available and make your own decision.

This article appeared in the September 2019 issue of Cessna Owner magazine. Read the full article including step-by-step photos here.

A quick suggestion

Most engines nowadays have a quick drain feature. If your engine doesn’t have a quick drain, forego the do-it-yourself oil change this time and have your A&P install one while they change the oil. It’ll make life much easier and far less messy when you take over the chore. (You can buy a Saf Air drain sump valve for less than $100. The part number is P5000 for all Lycoming engines and P6250 for all Continentals except the 0-300 and late C-145).

Tools you’ll need

You’ll need a quantity of plastic tubing with an inside diameter that will tightly fit the outside diameter of the quick drain nozzle; a small, flat pan; and a large bucket. You’ll need a 1-inch socket, a micrometer-type torque wrench capable of at least 0-50 foot-pounds, and some .049 safety wire for the oil filter. You can twist the safety wire with any good pair of pliers, but to do it easily and safety wire like the pros, you might want to consider buying an inexpensive pair of safety wire pliers.

If you’re on good terms with your A&P, you don’t need a filter cutter as you can probably borrow theirs, otherwise you’ll need to buy an oil can cutter (prices start around $70).

Lastly, buy some Dow Corning No. 4 lubricant, lay in a supply of shop rags, and you’re all set.

Here’s what you do

You’ve got the tools, a case or two of oil on hand, and the proper quantity of oil filters, so go flying to heat the oil, then park your baby and remove the cowling or cowlings.

Connect the tubing to the quick drain and open the valve. Draining the oil will take a while so use the time to inspect the engine and all its various accessories while you’re waiting. Check the battery and top off the brake fluid and maybe have a look at the nose gear strut for proper extension. If you’ve done all the inspecting you can stand and the draining is still in progress, go get a cup of coffee while gravity does its thing.

Once the oil draining has slowed to just a drip or two, close the drain. Make sure the valve snaps completely closed.

Move to the air filter and note how the safety wire is installed. The filter has to be safety wired to something on the engine, not to something on the engine mount or airframe. You’ll likely find that a hole is conveniently located on the engine near the oil filter mounting point — and that’s where the old filter is currently safety wired. Cut the safety wire and place or hold the flat pan under the filter. Use a ratchet wrench and the 1-inch socket to break the filter loose and screw it out, catching the leaking oil in the flat pan. Take the filter somewhere it can drain (into something that will hold a quart of oil) and leave it alone for a half-hour or so.

Take a shop rag and clean the boss where the new filter will mate to the engine, taking a look at the place where the filter’s threads will mate with the engine’s threads. If you find any damage, ask your A&P to take a look.

Assuming there’s no problem, coat the new filter’s gasket with a layer of Dow Corning No. 4 lubricant. (In a pinch, you can use engine oil, but a better seal will be made with the DC No. 4). You don’t need to pile it on — just a nice, even coating will do nicely.

Thread the new filter in place, making certain you’re not cross-threading it. It should spin right on with little resistance. If it gives you any hassle, stop and find out why.

After hand-tightening the filter, place the 1-inch socket on your torque wrench and tighten the filter to between 16 and 18 foot-pounds. After this is completed, safety wire the filter in place with a half-dozen turns or so on the wire and no slack in the run.

Check the drain valve again to make certain it’s completely closed, and then fill the crankcase with the recommended amount of oil plus one quart additional for the filter.

Clean up any spillage with full strength Simple Green cleaner and then a water rinse. (I mention Simple Green because it’s environmentally friendly and noncaustic). Use care to not get any solution or water on the magnetos or wiring.

After a half-hour of draining, split the filter open. Virtually all filters feed from the outside so you are unlikely to find anything on the inside of the filter but split it open anyway.

Carefully take a knife and cut the actual filter material away from the filter body and spread it out in an area with good lighting. Again, be very careful. The risk of cutting yourself is definitely present.

If you find anything with a part number trapped in the filter, you’re in trouble. More likely, you’ll find some carbon residue and a few flakes of paint from where you cut through the canister with the cutting tool. Any actual metal you find is something to take very seriously and you should call your A&P over for a consultation.

Crank the engine with the throttle as closed as you can get away with considering the temperature.

You definitely don’t want a full (or even half) throttle start with the filter empty of oil and the engine awaiting oil pressure.

Once the engine catches, verify you have oil pressure within 20 seconds or shut it down. With normal oil pressure, lean the engine until it almost stops and then richen it until it runs properly. After a minute or two (a minute in warm weather, a couple in the winter) advance the throttle and see if the engine stumbles. If it doesn’t sag, you can richen the mixture a bit and run it up to the rpm where you normally check the magnetos. Check the magnetos just for grins and then, if everything looks good, do a full power run-up for a minute or so and then slowly back the throttle down to idle. Taxi back to the maintenance area and shut down.

Exit the airplane and look for any signs of leakage around the oil filter or oil drain. If all is OK, reinstall the cowling(s), make your logbook entry by signing it off using verbiage something like this:

Date 05/15/19 Tach: 3,144.2 hours. Drained oil and refilled with [insert number of quarts, brand, and viscosity of oil here] and installed [insert make and model number of oil filter here] per [insert aircraft make and model number or make and model name here] service manual. Run-up OK. ss: John Jones, Commercial Pilot Certificate 999999999.

And that’s all there is to it. Fifty hours from now, do it all over again. The best part is that because you’ve already invested in the tools you’ll need to complete the job, you’ll really begin to see the savings.

This article appeared in the September 2019 issue of Cessna Owner magazine. Read the full article including step-by-step photos here.