I often see 100-107 degrees Celsius at 2550 RPM, which is quite close to the limit stated in the Continental engine manual (125 degrees Celsius). That can’t be healthy, no?
On the contrary, that’s nicely in the range of 165 to 220 F recommended by Lycoming. Continental engines use the same oil and have a similar limit of about 245 F.
Incidentally, after 40 hours it’s long past time to change to a decent ashless dispersant oil with anti-friction additives. That may reduce operating temperature a little. 100W and 20W50 have much the same viscosity at normal operating sump temperature.
Jacko wrote:
On the contrary, that’s nicely in the range of 165 to 220 F recommended by Lycoming. Continental engines use the same oil and have a similar limit of about 245 F.
That’s not what I see in the Continental Operator’s Manual:
The normal range is stated as 150-170*F, so about 65-77*C. This is way lower than the values that I see, and the ones for Lycoming engines that you mentioned. 30-40*C higher oil temperatures seem like a big deal — or am I seeing this wrong?
Interestingly, my cylinder head temperatures are at the lower third of the normal range (300-420*F). I would’ve thought that high oil temperatures would coincide with high cylinder head temperatures.
Incidentally, after 40 hours it’s long past time to change to a decent ashless dispersant oil with anti-friction additives. That may reduce operating temperature a little. 100W and 20W50 have much the same viscosity at normal operating sump temperature.
I did an oil change with mineral oil (Total Aero 80) at 25 hours after top overhaul. At 50 hours since top overhaul, I will do another oil change, and replace with synthetic oil (Total Aero D80). As far as I understand, those are the Continental recommendations … right?
Hi Zorg,
The accompanying text indicates that those figures in the generic TCM manual are for engine installations with an oil cooler. For typical installations with no cooler (C150 etc.) the green arc goes to 240 F (of course, modern synthetic oils can withstand much higher sump temperature). Unlike CHT, top of the green arc is good for engine longevity because it boils the water (a combustion product) and blows it out of the breather tube where it can’t rot the cam and followers.
Anyway, I really wouldn’t worry until you’ve changed to Total 15W-50 or similar ashless dispersant multigrade oil containing anti-wear and anti-corrosion additives. Opinions vary, but I can’t see any reason to delay that after bedding-in the piston rings. I’ve never known that to take more than about 10 hours.
Opinions vary about and synthetic and multigrade oil. Now that we have unleaded AVGAS it’s a toss-up between alleged corrosion and wear due to SAE 15 or 20 oil draining off steel parts if the engine is unused for long periods, and wear at each cold start with thick SAE 40 or 50 monograde oil. However I don’t think there’s any compelling evidence that the choice will significantly affect our overall cost of flying.
