Crankcase Oil?

Crankcase Oil?

Crankcase Oil?

If there was ever a sacred cow in engines, it’s motor oil. People get really passionate about
it, because “it works” and while that’s true, maybe – just maybe – there is something that is

What should you run in a V-twin?
Man, there are a million answers and opinions on that, but let’s start with some basics,
because the truth is, more folks are working on their bikes now than in many years due to
COVID. And, logically, more are wondering what oil to put in the engine.
ALL the oil in your crankcase has to do is provide a “cushion” of lubricant between the
moving parts of that engine.

  • When it’s hot
  • When it’s cold
  • When you start it
  • Under high rpms
  • Under idle

It’s got to move quick enough to get to the top end of the engine when that oil is thick and
cool and it’s got to not break down when it’s run for long periods in the heat.
In other words, oil has to “do” a lot, and the mere fact that so many different types are sold
to do that work is still sort of amazing to me. But buying motor oil in the store is a lot like
buying salad dressing.

A lotta damn options in the salad dressing aisle.
First things first – you need to decide what your bike was designed to run on.
A lot of v-twin engines are built to use 20W50, but looking up the proper oil for your bike is
always a great place to start. The real trouble begins when you have an older bike, or one
with a lot of miles on it.

That’s where you might begin to get suckered into buying garbage you don’t need – oils
with things like “high mileage” and “extreme environments” on the label.
For the most part, these are still motor oil, but – at least in theory – they have some magical
additives that will make your old engine into a new one. Guess what? There is no
“pourable” solution to solve aging seals and tired bearings.

Those of us who buy and sell old crap usually look to the oil in the crankcase first to see
what condition it’s in, and one of the first maintenance moves to make is to change the oil
and the filter. Truth be told, I never run synthetic oil in an engine I don’t personally know
the life story of. More than a few times, the very nature of synthetics has “cleaned” the
inside of an engine to the point that minor leaks that were “sealed” by regular motor oil
have begun to weep.

It’s annoying more than anything, but still something to think about.
I’ve never lost an engine doing this, but I seem to have created more small leaks after a few
miles of synthetic in an older engine. A seal here, valve covers there. Nothing big – and
really nothing unexpected – but still annoying.

One of the things some readers are going to flame me over is my habit of using “diesel
truck” grade oils in my older V-twin engines (and outboards, and flatheads). These almost
always have a few extras like zinc dialkyldithiophosphate (ZDDP) and while that’s NOT
great for catalytic converter-equipped gassers, it provides for additional anti-wear
protection in the oldsters.

If you’re running a pre-cat bike with some miles and can’t verify
the proper oil, this might be a solid standard to use.

The important thing about oil – assuming you’ve got the right weight of oil – it’s about how
often you change it. A lot of us grew up with “3 months or 3,000 miles” in cars, but what
about bikes?

A common rule of thumb I like is at least twice a year or every 2,000 miles. Yes, I realize
that synthetics can go up to 5 times that, but I don’t like the idea of anything sitting around
that long in a crankcase.

I’d rather do the maintenance and ensure I have clean oil regularly
than pay a premium for a lubricant that isn’t flushed out but once every two years. In the
case of a classic bike being stored for long periods, if the seals will handle it, I can certainly
rationalize keeping synthetic in it, but this would almost always be a trailer queen.
Now, I didn’t say too much about filters, but they create as many opinions as oil. This brand
is good, that brand sucks, yada yada yada.

The thing to remember is this: Harley may – or may not – actually build their own filters. I
found some references to the fact Champion used to build them, and now, they are being
built by Fram.

I’m not going to throw rocks, but I will say this: Fram’s reputation has suffered a great deal
in the last decade of so. Do your homework when it comes to sourcing high quality filters
and some names that have traditionally received high marks – Wix and Hastings. They are
rebadged by a lot of companies, but if you can cross reference enough and track them
down, they have been among the better filters I’ve used in a lot of applications. When it
comes to filters, pay attention to the filter, not the fad. Anti-drainback valves and filtration
media should always trump a pretty logo or a nut affixed to the oil filter body.

No matter which way you choose, please, please, please – change the oil and the filter. It’s
not hard, and if you have questions about your specific bike or model, chances are really
good you can find the video on YouTube to walk you through.