Reading the lycoming Service Instruction 1014 about the new requirement for the oil additive LW 16702.
I have been using Phillips XC 20w-50. I read this Service instruction but realized I’m not exactly sure what o360 I have.
Engine was purchased on a Sportsman I bought. Was built by Mattituk and is “not” an angle valve engine. The engine is a bottom intake but everything was converted over to the EFII fuel injection and electronic ignition. The plate on the side of the oil sump says TMXOF-360
It’s also constant speed prop.

In the service instructions it’s saying the lubricant additive must be used in the o360-E engines. So I’m trying to determine that I do or do not have a -E variant.

Is there something obvious that I can look for? I do not have any spec plates on the engine other than what mattituk put on.

Thanks. If needed I could provide pics of an area on the engine if that helps.

This page is your friend: http://www.meyette.us/LycomingEngineNumbers.htm

It can be found on the official Lycoming site too but it's in PDF form.

Designations usually distinguish engine designs by a few parameters (copied from the guide):

-Power section and power rating for the displacement
-Nose section (provisions for a prop governor, hollow/solid crankshaft, prop governor location)
-Accessory section (fuel pump type, acc pad(s), etc.)
-Counterweight application (if applicable, see the power section to determine this)
-Dual magneto design

I don't see many codes with -E. The only one listed has a dual magneto. In fact, I would guess it has something to do with the drive gears for a dual magneto because the engines excepted in SI-1014, the -H (320) and -E both used dual magnetos.

I would also guess you don't have a dual mag because they weren't that favored and probably not used for the Mattituck experimental engine.

Too bad Mattituck isn't still around to call and ask what exactly they built so you know for future reference.

It's safe to say you don't have an O-360-EXX engine. They made almost none of them. Do your best to avoid the LW16702 additive and oils that contain it. It is a friction modifier, which isn't great for ring seal. Can lead to higher oil consumption long term. It's necessary for the O-320-H2AD, and thats pretty much it.