The International Cessna^® 170 Association

Hello All
I am new owner of a Cessna 170B with C-145 engine, what is the best/correct oil? 15W50?
Thank you and kind regards from Switzerland.
Paul Misteli
HB-CYV

There is no "best" oil. You should use the oil that best fits the flying and the environment your flying in. Cessna lists straight weigh oils. Below 50 F (Continental says 40 F) they call for SAE 20, above 50 F they call for SAE 40. Now 40 weight is readily available from Aeroshell in their Aeroshell W80 but SAW 20 is not so common and I'm not sure it can be found anymore.

We have to remember that mulit weight oils like 15-50 or 20w-50 were not as common when these aircraft were built and oil technology has changed a lot and multi weight oils are just as good and even the new recommended oils.

So it comes down to personal choice.

Over the years I've settled on running SAE 40 in both by 170 and my Cub. I use Aeroshell W80 because that is what I can get. I rarely fly in temperatures less than 25 F and would preheat at that temperature or less so I get away with the thicker oil. I would not hesitate to use a multi-grade oil in colder temperatures. I personally like Phillips 20W-50.

I've also run Phillips 20W50 all year round. To be honest, for me, it almost comes down to what I have on the shelf.

Read "Oil Talk for Dummies " @ ECI2FLY.com, When you have ECI cylinders installed the manufacturer states that they would like you to use 20W50 Phillips from Day 1 to TBO.

http://www.eci.aero/pdf/breakininstructions.pdf scroll down.

There are many oils on the market that meet the requirements of a "EP" oil, (extreme pressure) shell uses a chemical called Tri cycel Phosphate that is a polishing agent used to adhere to the Lycoming AD for the H2AD engine, both major engine manufacturers have caution in their SBs warning to not use that in any engine with a friction clutch starter drive such as the 0-200 key starts and the 0-300-D angle starter drives.

and always add a filter to the 0-300.

I fly in Texas where average annual temps are 15 C or higher. I use AeroShell 100W which is a SAE 50 wt oil. This allows my oil temperatures to be higher (up to 240-F) .
If I flew in Switzerland, where lower temps were common, and where temps changed daily/regularly/unpredictably...I'd use AeroShell 15W50. But the Phillips 20W50 is also good.
Castrol also makes an aviation oil, and may be more available in Europe. Check this: http://www.castrol.com/castrol/faq.do?c ... Id=7005219

gahorn wrote:I fly in Texas where average annual temps are 15 C or higher. I use AeroShell 100W which is a SAE 50 wt oil. This allows my oil temperatures to be higher (up to 240-F) .

George where is that reference again. Was looking for it for my post earlier this thread and could not find it.

It's in the C145/O300 TCDS E-253 page 2.

NOTE 1. Maximum permissible cylinder head, barrel and oil inlet temperatures, 525°F, 290°F, and 225°F,
respectively.
Maximum oil inlet temperature limit is 240°F, when using Spec. MHS-24 oil SAE No. 50 above 40°F
ambient and SAE No. 30 or 10W30 below 40°F ambient.

That's where it is. I looked in the Continental Operators Handbook for it and it is not there. Forgot about looking at the TCDS.

Thanks Carl.

I have been involved in aviation in Alaska since 1978. I use 15W50 in winter and strait oil in summer. Some of my friends disagree with my opinion.

Aryana wrote:It doesn't get too cold out here in CA, but my engine is noticably happier with 15W50. Oil pressure and temp indications are less dramatic at start up and cruise.

Why would you need a 15 weight oil in any engine designed for a 40-50 weight oil.???

Besause it will crank easier on a cold day, and will act like 50 wt. when hot.

blueldr wrote:Besause it will crank easier on a cold day,

In Ca. ?

In Switzerland.

In the lower 48, it's good for lubricating the outside of the engine case seams, gasket parting-lines, etc..

One of the oddities I've experienced with the use of 15W50 was a decided reduction in oil-consumption immediately after an oil-change....then about 10 hours later, a considerable increase in oil consumption. By the 25 hour mark, it would be at/near the maximum I'd allow. Another oil change,...and it'd drop back down to near zero again....and then repeat, repeat, etc..

When I used straight-wt oil.... the oil consumption remained the same throughout the period.

I could only imagine the additives in that multi-grade/semi-synthetic stuff depleted as time was accrued and the consumption increased accordingly. (This experiment was conducted on one side of my Baron, with the other side using only straight wt 100W. And the multigrade side definitely stayed wetter with leaks. I even switched sides once and confirmed it was the oil...not the individual engine. It was a dramatic demonstration.)

That's another reason I use straight-wt oils. Clearly, this is a subjective experience.

Admittedly, Multi Vis oil is seldom needed in California, but way back in the dim recesses of my memory there lingers the delightful thoughts of a lovely young lady in the far northern part of our western states.
Occasional flights to where she lived, even in winter, were remarkably rewarding.
Straight weight oil is OK for old guys, but young guys gan get started faster, if need be, with 20-50.

olive oil works good for that

Rapid starting and a hasty departure ofttimes may be required because of an irate father, but even more so by an incensed husband. I sure wouldn't want a crankcase full of fat oil under those circumstances.
Can't you just immagine waiting for 40 degrees centigrade with "Dad" on the prowl with the old double barreled convincer, or, worse yet, the fuming spouse with the scalpel.