Just like cars airplane engines need periodic oil changes. Depending on the engine and usage frequency and pattern most casual airplane owners change their oil at intervals of between 25 and 50 hours. Since the Cardinal was not flown for several months while the purchase process was ongoing I wanted to change it out at the early end of that range.
After my last flight the oil was at 34 hours so I definitely wanted to change it out. I’ve been flying the airplane a fair amount and with many of those hours being long XC trips I will stretch out the next interval a bit father towards 40 or 45 hours.
I wanted to help out as much as I could and also get a chance to see under the cowling and to see the oil change procedure. So I did it together with my A&P but he did most of the work! The first step is to remove the cowling which comes off in a top and bottom half. The bottom half includes the landing light and taxi lights so you need to detach the wire connection to remove the lower cowl. It is also necessary to disconnect the cowl flap control cables and the nose gear door from the gear mechanism.
With the cowl off the oil can be drained. The drain fitting is a “quick drain” style so all that is needed is to put a rubber hose on it and push up to start it draining. We just left the oil draining while moving on to the filter and draining the oil cooler.
The oil filter is a spin-on type much like many automotive applications. One difference is that the aviation oil filter includes a tab for attaching safety wire. The safety wire is twisted tight to oppose the direction of loosening and helps to ensure that while unlikely any vibration loosening of the filter causes a slow leak instead of a catastrophic failure. The oil cooler drain nut also received the safety wire treatment.
At this point we pushed the plane out of the hangar and did a very brief start and run up with the cowl off while my A&P walked around looking for any leaks. With everything checked out we pushed the plane back into the hangar and wrestled the cowling on. Getting the cowling on is definitely easiest with two people and requires a fair amount of jockeying to get everything lined up.
I am using Philips XC 20W-50 oil. From the research I have done it seems to offer a good price/performance point relative to multigrade oils from Aeroshell and Exxon. It seems to enjoy a good popularity among airport locals. A straight weight oil would be OK for the summer months here but New England weather is unpredictable enough that I’d rather just stick with a multigrade oil year round.