Contributed Tech Stuff - Oil & Filters

Contributed by F. Robert Falbo


Disclaimer: Information and ideas contained in this section are solely those of the contributor(s) and not those of Harley-Davidson®, Harley-Davidson® of Uica, H.O.G.®, or the Erie Canal H.O.G.® Chapter.



Oil...it's a slippery subject! Everyone has an opinion about the oil they use, and the filter they choose. The trouble is that most people's opinions are based on anectotal evidence and not on facts. So let's go over a few facts...

Harley specifies a 20w-50 motor oil. People used to think that the "W" stood for Winter - it doesn't. It has to do with the testing standard used to determine how to grade the oil. The first number references the oil's viscosity (how easily it flows) at around 70 degrees fahrenheit, and the second the viscosity at around 212 degrees fahrenheit. (The numbers refer to the relative "weight" of the oil, but not it's actual viscosity, which is a totally different number.) I'm not that familiar with the viscosity requirements for Harley's motors, but using a car motor as a reference we can understand the basics. Car motors require an ideal viscosity of 10 @ 212F. A single weight oil would be fine if it met that requirement and the motor always stayed at 212F, but motors get shut off and cool down. At 104F the viscosity would increase to 100, and at freezing (32F) it's up to 250, and as the temperature keeps dropping the viscosity keeps going up until the oil no longer flows, and remember - FLOW is the most important factor in lubrication - not pressure.

All oil, whether natural or synthetic, starts out as a single weight. Manufacturers use additive packages to modify how the oil performs throughout the expected temperature range it will be exposed to. These additives attempt to limit the change in viscosity within that temperature range to the requirements expected by the motor's manufacturer. As I stated before, automotive motors typically require a viscosity of 10 at operating temperature of 212F, which a 30 weight oil is fine for. But starting the motor at 70F, the viscosity might be around 50 or more! Using additives, Manufacturers modify the oil so that it acts like a 10 weight oil at 70F, which may have a viscosity of around 25, making the oil flow quicker through the motor at startup. Hence labeling the oil a 10w-30.

A Note on Weights: I've seen some people claim that they use 15w-50 or 10w-60 in their bikes instead of the 20w-50 Harley recommends. If you run your bike in cold weather, it will help when starting if you use a lower cold-weight number oil, but using a higher weight oil for normal running isn't a great idea, since you're actually decreasing the oil flow by increasing the oil's viscosity when hot.

Natural or Synthetic? The argument goes like this - "If you change your oil at regular intervals there's no need for a Synthetic oil." My answer to this is that if you live in the tropics where it's 80F all year long, that may be true, but we don't. One of the big advantages of Synthetic oils over Natural oils is that they require fewer additives to stay within viscosity range - they thicken less in the cold, and thin-out less when heated. The most wear on your motor occurs when it's started cold. The quicker the oil flows through the motor, the less wear on the bearings & parts, and Synthetic oils just plain do a better job of flowing quicker than Natural oils. That's been proven time and time again, in test after test, but there's still many Luddites out there that refuse to believe it. Also, as the additives wear out, the Synthetic continues to provide better protection for your motor for longer - that's why you can get by with longer oil change intervals if you need to.

My choices: Two bikes - two different oils. In my older (2013) bike I use Amsoil V-Twin 20w-50 Fully Synthetic oil. In my newer (2017) bike I use H-D™ SYN-3 20w-50 Synthetic. When the Amsoil I have stocked is finished I'll be switching both bikes to Mobil 1 V-Twin 20w-50. Why?... Because I can get it locally for $7.99/Qt, and none of the other synthetics have shown me they're worth $5+/Qt more than Mobil 1 V-Twin 20w50.


Oil Filters: Where to begin? Oil filters elicit the same reponse as oil - everyone's got a favorite, and everyone knows a horror story - not to get into all those videos on Youtube with self proclaimed experts cutting open oil filters! It's enought o give me a headache. I'm certainly no expert, but I have formed a few opinions based on the information I've absorbed over time. So here they are...

Replaceable basic oil filters are pretty much the same inside - they all use a type of resin-inpregnated filter paper to trap particles from re-entering the engine. They all have a spring-loaded bypass valve so that if the pressure is too high the oil can bypass the filter element and reach the critical engine components. When you change the oil, you unscrew the old filter, screw on a new filter, and chuck the old filter out.

Reuseable oil filters are a bit different. Rather than a paper filter element they use stainless-steel, with laser cut filter holes. This filter element can be removed, cleaned, and reinstalled. They also have the prerequisite bypass valve, but they claim to flow more oil through their filter on initial startup than paper elements.

My choices: I have two bikes - My older bike (2013) one has a reuseable filter and the newer (2017) has the standard black H-D™ filter. I may change to reuseable filters on both bikes once the waranty expires.


OILS

MANUFACTURER PART NUMBER PICTURE TYPE PRICE/QT COMMENTS
HARLEY-DAVIDSON 20w-50 NATURAL $7.49
HARLEY-DAVIDSON SYN3
20w-50
SYNTHETIC $12.95
AMSOIL V-TWIN
20w-50
SYNTHETIC $13.45
EXON/MOBIL MOBIL 1
V-TWIN
20w-50
SYNTHETIC $9.54
REDLINE OILS 20w-50 SYNTHETIC $15.95

FILTERS

MANUFACTURER PART NUMBER PICTURE TYPE PRICE COMMENTS
HARLEY-DAVIDSON 63798-99A REPLACEABLE $11.95
HARLEY-DAVIDSON 63798-99A REPLACEABLE $14.95
K&N ENGINEERING KN-171B REPLACEABLE $16.00
K&N ENGINEERING KN-171C REPLACEABLE $20.50
PC RACING USA FLO
PCS4B
CLEANABLE/
REUSEABLE
$120.00
PC RACING USA FLO
PCS4C
CLEANABLE/
REUSEABLE
$120.00





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