Engine oil

[BigEndBob]

Just running in a Lycoming engine in a Tomahawk, club use, so far 1 litre used in 25 hours.
So what's the opinion on the best oil to run it on in the future.
Should i go multigrade, but have used that in other engines and not too impressed on the consumption seen.
Or stick to good old faithful single grades.

[Curlytips]

A lot will depend on your operating conditions particularly temperature. Here in Blighty, multi grade 15/50 works well all year round, so no need to mess around when the seasons change. As soon as my new Lycoming was run-in, I went for Aeroshell product and 850 hours in, not missed a beat. A big plus is that it complies to Lycoming spec to allow unleaded to be used, so I can use UL91 if available (and if competitive!).

[MrAverage]

We've "broken in" quite a few lycoming cylinders recently and always go on to W100 Plus at 50 hours. (Obviously straight for the first 50) According to all my trusted engineer friends, the most important thing is that the first 2 hour flight needs to be done correctly.

[Curlytips]

Yes, you need to grind it in properly over first few hours, with high power settings, or your future oil consumption will be higher. It's a good time to decide which oil you will use long-term, as if you run on W grades for a long time, then switch to multi, you risk some gumminess from deposits from previous oils. So if you want to go multi in a new engine, do it as soon as you finish the straight.

[Fostex]

Most engines have a specific run in plan, consult the manufacturer. I have run in a completely overhauled O320-D3G recently and did so with a 3hr test flight at a variety of power settings as per the Lycoming recommendations.

This was something like

Warm/up T/O - 15mins
75% power - 60mins
65% power - 15mins
75% power - 15mins
65% power - 15mins
75% power - 15mins
Max power - 30mins
Landing/Taxi - 15mins

The key thing is to have long flights at 65-75% power early in the life of an overhauled engine.

We were on straight 80 for the first 50 hours and complete oil and filter changes every 25 hours during that period if I recall correctly. Oil test and particulate analysis after each oil change. Important to closely monitor oil consumption so that we could check the piston rings and cyclinders are wearing in against each other. Straight 80 encourages this wear vs the normal synthetic lubricant used in day to day ops.

[BigEndBob]

Well the Tomy engine does seem to be bedding in nicely, based on oil consumption.
But other engines i am experiencing, are burning oil like no tomorrow.
I think there is some variation on who is rebuilding these engines.
The only problem with the multigrades are they have the consistency of water when hot.

[Fostex]

Good article from Shell aviation - https://www.shell.com/business-customers/aviation/aeroshell/knowledge-centre/technical-talk/techart08-30071255.html

[Pilot DAR]

From my experience with 3000 hours on my O-200, I will never again run any multigrade in it. If the temperature is close to freezing when I plan to start, I will properly preheat. I don't start cold engines, so I don't need multigrade. For my two Lycomings (O-320 & O-360) they seem to be more tolerant of multigrade. They were both operating multigrade when I bought the planes, though I have since changed them to straight 80, and again, am careful to preheat when appropriate. I did not find the operational difficulties with multigrade in the Lycomings as I did in the O-200, but I changed anyway to run common oil in all. With preheating and proper winter baffling, I do not find multigrade to be beneficial enough to overcome the added cost and difficulties with possible viscosity breakdown.