Franklin Engine - Oil Viscosity

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scottj33gm

New member
I am new to the forum and a new Bellanca owner. My Bellanca Cruiseair has a 165 HP Franklin with 245 hours SMOH. The gentleman I purchased the aircraft from said to never run multi-viscosity oil in the Franklin engine. Others on the airfield say otherwise, especially with the colder weather. I'm at the point that I need to change the engine oil, but I'm getting mixed signals. I've looked through the forums and have read responses from other Franklin owners that support either case. (Straight viscosity and multi-viscosity). If I run straight viscosity with the colder weather, should it be 30 or 40 weight? If I run multi-viscosity, should it be 15W-50? Thanks in response for your help. BTW, I enjoy reading the forum.

Scott
 
What part of the country are you in? There is cold and there is COLD. I have good luck with Phillips XC20-50 and Aeroshell 40W. If it is COLD, you'd better be pre-heating, as well.
Dan
 
Hi Dan, I'm in cold country. 15 years in Minnesota COLD country is enough to last one life time. I'm in northern Nevada, Fallon to be specific. I don't have a engine crankcase heater, somehting that I would like to know more about for the Franklin engines. I do preheat the engine overnight with an electric oil filled radiator heater. Surprizingly it does a really good job of getting the engine warm. It takes heavy blankets over the engine cowling and some patience, but it's better than starting a cold engine. My concern is that if I fly out of town in the winter and leave the bird outside overnight, I won't have my poor mans engine heater. That's where the oil viscosity comes into play. Thanks for your help.

Scott
 
Hi Scott,
I am surprised that there aren't numerous replies to your question. It is like asking about mogas...everyone has an opinion, but often little actual engineering data to back it up. So, I will just give you my experience...and also my opinion.

I have used AEROSHELL 15-50 for the last 20 years/1200 hours in myF150 powered Cruisair with an oil filter. I just decided to switch to Aeroshell 100W for this last summer, and back to 15-50 during the winter here in mild (but wet Eugene, OR). I seem to recall that Greg Lucas said not to use multivis when he worked on Franklins, but then Gene Hamilton told me that it was ok, so...? I should let Greg speak for himself, I think he is still on this Forum. The plane used 15-50 when I got it, and the previous owner who overhauled the engine with Gene said to use it.

My engine is using oil now...1 qt in 4 hrs, but after all this time, I am not complaining. When I first got it, I swore people were sneaking into my hanger and pouring oil in to it between flights just to drive me crazy (a short drive!) 'cause it never seemed to use any between changes!

So my opinion, for what ever it is worth...Oil has improved incredably since our engines were designed, in fact many attribute that to why newly certified engines have such greater TBO's than engines designed in the 40's and early 50's. Our engines can and some do go to 2000 hrs before OH (at least in some Stinsons). Also, you can see that TBO have increased on older engines too. So, I think that you really aren't going to see that much of a difference between different brands of oil. I would still not mix different brands, but I did talk to a tech rep at Shell, and he told me that you can mix 15/50 with 100W (!?) but I guess I am still old fashion enough to try not to mix oils. So, my recommendation...pick one that you feel good about and see how it behaves in your plane.
Larry
 
Hey guys my problem with any multi vis oil is it breaks down fairly quickly to 15 or 20 weight. I noticed when tearing down engine that the bulk that used multi had much more wear than straight weight oil. Nearly always had to toss the cam and grind the crank. I don't run multi in any of my engines now, Franklin or Continental. We have a guy on the field that flies pipe line patrol, he kept sticking valves in his Lycoming. I switched him to Aeroshell 100W plus and he uses a crankcase heater in the winter. No more stuck valves and that is all we changed. Greg
 
I have a letter written by the Franklin Engine Company in the late 60's or early 70's ( by which time modern ashless disperant av oil was available). In it they reccomend single weight oil such as Aeroshell 80W ( 40 wt).

I think the viscosity specs found in the original engine manual are still germain.

Previous comments are spot on... oil technology has progressed light years since the 40's.

We wouldnt think of running non-compounded oil all the time.. but that is essentiall what oil was back then. The metallic anti-wear additives, and anti corrsion additives, and detergent and carbon dispersing additives common today weren't even a wet dream then.

Or at least they were as rare as the no-lead aviation gas the franklin was designed to run on is today !

The original 650 hour TBO reflects that.
 
Unleaded avgas disappeared in the early '50s. There wasn't enough lead in the new 80/87 to bother the Franklin. I found out early in my experience with Franklins that 100/130 was detrimental in the long term. I don't think 100LL is much better. Though it is not STCed for the Bellancas, I think unleaded mogas is the best replacement. You can find local suppliers of unleaded, non alcohol fuel through "purefuel.com." There is plenty demand for this fuel from vintage automobile, motorcycle and all two stroke outboard owners.
Dan
 
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