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A scientific approach to oil


New Englander

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There's always lots of anecdotal oil talk here and lots of popcorn time. Some will say if you don't use the oil they love then you should be condemned to driving green tractors.

One of the areas of concern is flat tappets with some advocating lots of zinc additives, straight weight oils, multi grade oils, favorite brands and some snake oils.

Well, I happen to own a Norton Commando, a bike long out of production but still actively ridden and raced. It's a flat tappet engine of ancient design grown through years from its '40s design. Tappet and cam wear has always been a problem.

An engineer on the Norton site I follow had enough of anecdotes and manufacturer's claims and decided to actually test as many oils as he could. He used a scar tester with an ability to heat and load the oil to film failure.

Attached are his findings. It's lots of reading but you will see some oils not advertised as motorcycle but general synthetics, even Rotella. He comments on each oil on the raw data graphs on such things as suitability for wet clutches, air cooling, water cooling, etc. None of this data may apply to tractors but may be of interest for your other engines, especially those with flat tappets. This data may not show correctly on a mobile device.

The time and expense spent on this was extraordinary!

https://www.accessnorton.com/Oil-Tests/NortonOil.php

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1 minute ago, lightninboy said:

So, what's the conclusion?

Ah! Well, one thing I notice is that Aeroshell W100 plus, and aircraft oil, flunked so miserably that the tester commented to the effect that it be relegated to cabinet hinge oil. I use Phillips 20-50XC which wasn't tested.

I concluded that I'll probably switch to one of the Rotellas tested for my Norton as I want to move to a somewhat lighter oil than the 20-50 MC oil I'm now using.

You can draw your own conclusions based upon the test results. I suspect the aircraft oil tested flunked miserably due to the fact the formulation is old, very old due to the expense necessary to get it FAA and manufacturer approved for aviation. There are other aviation oils tested that did quite well but they're specified for experimental and light sport aircraft which only require manufacturer approval, not FAA.

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2 minutes ago, RichardDSalyer said:

I will play stupid and ask why is an oil comparison study for a British motorcycle important on a tractor forum?

I answered that in the post: "None of this data may apply to tractors but may be of interest for your other engines, especially those with flat tappets."

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8 hours ago, New Englander said:

Ah! Well, one thing I notice is that Aeroshell W100 plus, and aircraft oil, flunked so miserably that the tester commented to the effect that it be relegated to cabinet hinge oil. I use Phillips 20-50XC which wasn't tested.

I concluded that I'll probably switch to one of the Rotellas tested for my Norton as I want to move to a somewhat lighter oil than the 20-50 MC oil I'm now using.

You can draw your own conclusions based upon the test results. I suspect the aircraft oil tested flunked miserably due to the fact the formulation is old, very old due to the expense necessary to get it FAA and manufacturer approved for aviation. There are other aviation oils tested that did quite well but they're specified for experimental and light sport aircraft which only require manufacturer approval, not FAA.

Has there been many survivor stories from a oil related failure on a Lycoming or Continental? 

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9 hours ago, RichardDSalyer said:

I will play stupid and ask why is an oil comparison study for a British motorcycle important on a tractor forum?

because there are LOTs of tractors with motorcycle engines in them and they go REALLY FAST and make LOTS OF NOISE - some turning 15K ++ RPMs 

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3 hours ago, jeeper61 said:

Has there been many survivor stories from a oil related failure on a Lycoming or Continental? 

Interestingly I replaced all 12 of the lifters in the Continental O470 engine that powers my 182 due spalling on the lifter faces. Borescope showed the steel camshaft looked ok but I still have to pull the lifters for inspection in a year. Lifters are chilled iron. I'm not looking forward to it as the intake and exhaust has to come off along with the lower spark plugs/ leads and all the CHT and EGT probes. Lifters are $200 each and the gasket and hose set added a few hundred more.

Lycoming engines have the most problems with cam and lifter wear thought to be mostly caused by the location of the camshaft at the top of the engine. Continentals somewhat less thought to be because the cam is located under the crankshaft and receives oil dripping from it. The crank having quite a bit of oil in it slowly dripping from the bearing journals preventing or at least limiting rust from forming. Aircraft engines often sit unused for long periods unless in commercial service.

My plane sat for long periods before I bought it so perhaps that's where the spalling stems from but the results from the test I provided says perhaps the old time aviation oils aren't the best. Luckily Continental lifters can be replaced without splitting the engine case; Lycomings have mushroom tappets that require splitting, a major issue.

I provided the testing information for just that, information that's not anecdotal. I find it quite illuminating that there's such a spread in load performance among oils and don't want to base my choices on someone's say so or worse. Obviously information such as suitability for wet clutches has no bearing on anything but motorcycles. I was pleased to see Rotella oils do fairly well. 

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Rotella T6 is my go to oil.  I have had good test results from it in my 2006 F260 with the 6,0 diesel which is notoriously hard on oil.  I even went 15 k on one oil change without beating the oil to death.  I have 235k on it now with no major complications.  I use it in everything gas and diesel that doesn't have a more specific oil requirement.

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