Oil choice for M20C / lycoming O-630

[rwabdu]

Would appreciate some opinions on preferred oil for a m20c with a lycoming 0-360, 180 hp. I know there are a million posts on this but:

Live in Michigan (cold and warm at different times of the year). Currently running Phillips X/C 20W/50 with camgaurd. Engine has ~1000 hours, previous owner was using Aeroshell 15W50... some at my local airport have urged me to switch to Areoshell 100plus to protect the camshaft from corrosion. The airplane has sometimes not flown for up to a month to a month and a half with a few maintenance issues. Also has some carbon in the cylinders from manifold intake leaks that are now fixed, but need to work on burning that stuff out of there. 

[Mooneymite]

I'm not sure there is a wrong oil as long as you use one for your temperature range and meets engine specifications for oil.

While certainly there are differences in oils, and changing oil frequently is never going to hurt your engine, I'm not sure all the bruhaha about what oil is "best" amounts to much.  Today's oils are all superlative compared to what was being used when our engines were originally certified.

When I bought my Mooney years ago, the previous owner was using Havoline 10W-30.  Yes, car oil.  I bought it with about 1700 hours on it and switched to Aeroshell W100.  The engine was running fine at 2400+ hours when I exchanged it for a factory reman.  Everyone has their favorite oil story, but generally when an engine fails, it is not an issue related to oil type, or brand. 

Buy what you like, run it for 2000 hours and let us know how you like that oil.  If it is a bad oil, we'd all like to know!

Edited February 19, 2022 by Mooneymite

[markgrue]

I run 15W50.  I do not know of any modern aircraft oil that is bad.  I personally do not think that straight weight oil is a good idea as I think the temp changes too drastically and I like the detergent qualities of the multi viscosity oil.  I don't understand the concept of it being better for the cam.  I f someone wants to run it then fine.  I don't do that.   Just my opinion mind you. 

 

Mark 

[A64Pilot]

Shell’s best / Premium product is their 15W-50. There is no plus 15W-50, it’s all plus.

I can’t make a case for running straight weight oil, some say since it’s thicker it stays on the cam better for better corrosion protection.

But here’s the thing, when 15W-50 is hot, it has the same viscosity as straight weight 50, any oil that's going to drip off will do so when it’s hot and thin. I don’t know about others but it’s rare for me to shut down a cold engine, usually I’ve been flying when I shut down for the day.

So it’s actually not thicker when the oil will drip off.

Dont understand how carbon will form in cylinders from an intake manifold leak?

Don't run Auto oil for any reason, it’s not been formulated to dissolve lead for a very long time, by not being able to carry the lead in suspension you end up with sludging ala the Mobil Av oil problem of years gone by.

There is a pretty strong case to burn a good Diesel oil in Experimental aircraft that only run Auto fuel though, the older Diesel oils have the high pressure anti wear additives that were removed from car oils because they reduce the lifespan of catalytic converters, the newer Diesel oils have it removed as the newer Diesels are also running Cats now.

Edited February 19, 2022 by A64Pilot

[jaylw314]

Lycoming recommends (by SB) a specific additive for Lycoming motors, which is the "plus" in some oil names.  It's an anti-scuff additive, not specifically an anticorrosion agent, so switching to a "plus" oil will not, by itself, improve corrosion resistance.

IIRC the camguard product includes that additive among other things, so adding Camguard to a "plus" oil would be a waste of money.

I can't remember any of the above specifics, but I know somebody here does if you need it, these guys are like walking encyclopedias  

FWIW, I've been using the new Phillips Victory 100W Plus oil the previous year because it's the cheapest additive oil right now

[PT20J]

Lycoming SB 446 and AD 80-04-03 requires the use of LW-16702 (TCP) in certain engines. TCP is an anti-wear agent that works by promoting an oxide layer on the surface of metals. The oxide layer is sacrificed during startup to protect the metal beneath until there is sufficient oil film for boundary lubrication. After shutdown, a new oxide layer forms. This action reduces wear, but does not completely eliminate it since the oxide layer is formed from the metal itself. TCP is a significant health hazard  https://en.wikipedia.org/wiki/Tricresyl_phosphate

Lycoming SI 1409 permits its use in all Lycoming engines.

LW-16702 is not a corrosion inhibiter. Camguard is an corrosion inhibiter with other properties. It is not a permitted substitute for LW-16702 by those engines affected by the AD.

The idea behind the oils with LW-16702 added was to avoid the hassle of having to mix in the additive with every oil addition in engines required by AD to do so. I believe both Philips and Aeroshell blended oils use TPP which is similar to TCP but supposedly less hazardous to your health.

Continental and Lycoming are agnostic about what oil to use so long as it meets their specs (which ALL aviation oils do).

Aeroshell 15W50 is a semi-synthetic blend. There is some anecdotal evidence that it might not be the best choice for engines that do not fly often. I replaced the engine in my 1994 M20J in 2018 at 1100 hours and the camshaft was spalled. The engine had been IRAN'd previously at about 750 hours in 2003 for a spalled camshaft by the previous owner. Both previous owners had used A/S 15W50. I don't know if that had anything to do with the camshafts or not, but I'm using Phillips 20W50 and Camguard and no LW-16702. 

Skip

[Ragsf15e]

20 hours ago, jaylw314 said:

Lycoming recommends (by SB) a specific additive for Lycoming motors, which is the "plus" in some oil names.  It's an anti-scuff additive, not specifically an anticorrosion agent, so switching to a "plus" oil will not, by itself, improve corrosion resistance.

IIRC the camguard product includes that additive among other things, so adding Camguard to a "plus" oil would be a waste of money.

I can't remember any of the above specifics, but I know somebody here does if you need it, these guys are like walking encyclopedias  

FWIW, I've been using the new Phillips Victory 100W Plus oil the previous year because it's the cheapest additive oil right now

I was waiting for @PT20J to comment on that one because his posts are well thought out and have good documentation… the additive in the lyc sb is only for certain engines, not o-360s or io-360s, so not required here.  You can use the Liberty Oil with the additive but you definitely don’t need to.  
 

Personally, I use a multi weight because I live somewhere dry with large temperature swings and I don’t want to end up with 100w oil and cranking at ~30 degrees  f (below that I’d be preheating).  I use Phillips oil because I’ve found it cheaper than Aeroshell multi and because of the synthetic mix in aero shell that may or may not be great for the engine.  Finally, I use camguard because, why not?  It’s probably not going to hurt, and it’ll likely help someone, why not me?  As long as you use an approved aviation oil, you’ve got a 90% solution.

[cliffy]

Just for fun-

And then you have MMO and STP

[jaylw314]

3 hours ago, PT20J said:

LW-16702 is not a corrosion inhibiter. Camguard is an corrosion inhibiter with other properties. It is not a permitted substitute for LW-16702 by those engines affected by the AD.

Ah, I thought I had recalled hearing somewhere it was in there, thanks for clarifying!

[dylanac]

For the most part, 20W-50 is the default choice for most engines. It does a good job of keeping everything clean and slick. If you let you plane sit for weeks at a time and/or live somewhere without large yearly temperature variations, going with a single weight such as W100 might be a good choice. The idea being the single weight is thicker at room temperature so it sticks to parts longer, providing rust protection. The exception to all of this being any oil that needs LW-16702. You can buy the additive and add it to any oil or buy oil with it already included, such as Shell oils with the plus designation. I personally steer clear of the 15W-50 as I haven't heard the best about engine cleanliness with it. You're also not going to get great rust protection out of it, being so thin. Additionally, there were some issues with synthetic aviation oils not being able to properly scavenge lead from piston rings. While this is a semi-synthetic, it's not something that's worth the risk when I feel 20W-50 is better (and happens to be much cheaper). I order through aviation oil outlet. Anything over $75 is free shipping so I get 2 cases at a time for $136 shipped. Hard to beat $5.67/qt. At the end of the day, the best oil is one that is changed often. I do mine every 25-30 hours.

13 hours ago, cliffy said:

Just for fun-

And then you have MMO and STP

Oh boy, here we go! MMO ftw!

[rwabdu]

Thanks for all your advice! Sticking with Phillips X/C 20W/50 & Camguard. 

[philiplane]

Phillips also makes Victory 20w50, which has the Lycoming anti-scuff additive. Anything that helps lengthen the life of the cam and lifters is a good value.

The engine shops I work with all tell me that:

1-an engine that's been on Camguard has much cleaner insides than others.

2-for engines run on Shell 15w50, that the synthetic blend tends to promote seal leaks, and there is more lead sludge stuck everywhere. On the many engines that I have switched from 15W50 to 20W50XC, I can confirm this. The leaks stopped. 

And, the reason that single weight oils offer longer protection after shut down, is that the multi-weight oil continues dripping, because it thins as it cools, back to the base weight. 15w50 is a 15 weight oil, that acts like 50 weight when hot, then thins back to 15 weight as it cools. So it drips off surfaces for much longer, and leaves a thinner coat in the process.

Edited February 21, 2022 by philiplane

[Ragsf15e]

8 minutes ago, philiplane said:

Phillips also makes Victory 20w50, which has the Lycoming anti-scuff additive. Anything that helps lengthen the life of the cam and lifters is a good value.

The engine shops I work with all tell me that:

1-an engine that's been on Camguard has much cleaner insides than others.

2-for engines run on Shell 15w50, that the synthetic blend tends to promote seal leaks, and there is more lead sludge stuck everywhere. On the many engines that I have switched from 15W50 to 20W50XC, I can confirm this. The leaks stopped. 

And, the reason that single weight oils offer longer protection after shut down, is that the multi-weight oil continues dripping, because it thins as it cools, back to the base weight. 15w50 is a 15 weight oil, that acts like 50 weight when hot, then thins back to 15 weight as it cools. So it drips off surfaces for much longer, and leaves a thinner coat in the process.

Agree with you in general, but the anti scuff additive is only in the lyc SB for certain engines as noted above in PT20’s post.  I’m not so sure it’s doing anything for other engines.  Thus for most of us, 20w50 is fine vs the Victory oil.

[Guest]

LW-16702 anti scuff agent was designed to improve the life of the cam and lifters in the O-320-H2AD in the late 70’s 172 and other Lycoming 76 series engine like the O-360 in the Piper Seminole.

Clarence

[philiplane]

https://www.aviationconsumer.com/maintenance/phillips-66-new-oil-lycoming-additive/

[1964-M20E]

the best oil is circulated oil, fly often my friend.

I run P66 20W-50 or any other aviation piston oil if needed.  I know some who won't run anything but Shell 100W to each his own.