There's an older youtube vid I can't find where a garage guy set up a test to test the real viscosity characteristics of both dino & syn in single and multi weights at temp. 50wt and 20-50, used popular name brands.

Heated each to a common running temp then poured through a viscosity meter used for paints, timing the recording. Predictable results, the syn ran like water through the test including the single weight. 20-50 was considerably thinner than the straight 50. I've never bought into the whole it's same at operating temps speel. My only real issues with syn's is it wants OUT by it's very nature and the motor in noisier, you hear more mechanical rattles. In newer tighter tolerance machines it's good stuff older higher wear engines will seep at seams and bleed with old seals. Never put that **** in an old shovel, the new repop S&S and the like engines can handle it but you hear more motor noise.

Staying with dino till I can't, leave the syn for the toyota motors in my trucks.

 

[QUOTE=98hotrodfatboy;20911908]As it says.. Is it absolutely necessary to run Synthetic oil in my 103 Twin Can.. Or, can I use Valvoline VR1 high zinc Dino Racing oil?
the motor has a slight build.. Specs in the SIg/QUOTE]

Just about everyone here knows VR1 is all I've ever run including in my 127hp 107 build. Far better choice than any MC oil. Synthetic or otherwise.
Any race oil is. MC oil lacks friction modifiers so it works it wet clutches. Those FM are an added layer.of protection in an engine.
That said, VR1 Conventional works as well or better in air cooled v-twins according to UOAs than VR1 synthetic and has a higher Flashpoint.

a little buying tip...I've always bought it by the case on Amazon for like $5.30/qt til a girl at NAPA created an Ag account for me and I've been getting there ever since under that ag account for 3.99/qt.

 

speaking of viscosity.
I'll share an anecdotal..

back in the day I had a tired old Ford van with mega miles.
when warm, the oil gauge would drop low-low sitting at a light or stopped in traffic.
Right after an oil change, it was more normal, but didn't last long.

Learned a lesson when I was kid and blew up my mini-bike*
became pretty **** about oil after that.
I rolled a lot of miles and changed oil religiously at 3000 miles.
Tried all the major brands of the day (Castrol, Quaker, Shell, Penn, Valvoline, etc)

all of them lasted appx 600 miles before oil gauge dropped low at idle again....except for one.
Valvoline lasted appx 1200 miles before the drop
I determined (rightly or wrongly) viscosity break down was the reason
Became a fan of Valvoline (though I don't hesitate to use other oils too when on sale)


*the greatest lesson I learned from my mini-bike?
Prob'ly not as important "what" oil, but to at least make sure there IS oil in it...


.L.T.A.

 

I ran conventional VR-1 in my '91 FXSTC because it was popular with the guys racing Porsche 911's. I did not have any issues. I know your question was directed at TC's but I'm sure your AFR is richer than stock so the operating temps will be similar. The "R" in VR-1 denotes "racing" and the oil is targeted for extreme duty. My $.02 is that I don't want to hear my valvetrain clattering when I have hydraulic lifters, whether the noise is caused by the oil or the cams.

 

I like the, "Break it in on conventional" thing. Always makes me smile. Can anyone tell me what property of conventional oil makes it more suitable than syn for break in?

I'm going with price. If you're going to dump it early on a break in why spend extra on syn.

 

Syn oil? It depends….

With stock, and you aren’t in heavy traffic in hot weather, or ride really hard. Good Dino is fine.

 

You're talking about the channel called Project Farm.

It also seems that you interpreted the results backwards. A thinner viscosity that still lubricates at the operating temperature is better at preventing wear.

I also haven't experienced the leaks that supposedly happen with synthetic oils in any of my vehicles.

I never used to be such a fan of synthetic oils but what essentially changed my mind were how much nicer my Diesel engine starts with 5W-40 when compared to 15W-40 even within the temperature range where 15W-40 is approved by the manual, the results of oil analysis when I sent pitch black oil to get analyzed after 15k miles and they said it was still good, and the temperature stability that it offers for air cooled engines like our Harley-Davidsons.

 

I use Spectra dino oil and I don't change twice as often. What do you have to back that claim up? I ride in Florida in high heat and never a problem and I sure don't change oil at 1500 miles like you claim.

 

Apples verse's oranges in this debate, cold start and heavier oils are only an issue with auto solid sleeve engines with lager area mating surfaces where the tighter tolerances the heavier oils increase the shear pressure needed to break the seal on the moving parts. Temps drop this increases as the oil weight does.

Harley engines are mostly larger hard surface barrel & ball bearing assembly, running bushings are small and few so hold little impact on the issues sleeve bearing engines will struggle with, down side with syn and lighter oil in those is you will hear more mechanical noise.

Short of it is. lighter is fine in the car or truck, the harley doesn't need it.

 

I agree with TwiZted, our motors do not have Babbitt style bearings that are running two to two and a half thousands clearance where we need the oil to act as a cushion between the bearing and the journals on the cranks.. Our rod and crank pin bearings and our opinion and sprocket ship bearings are totally different shear is not relevant when it comes to these motors.. However lubrication is, and the only time we hear any noise when it comes to lubrication or thin oils is when it comes to the valve train.. If you ever hear noise from your crank pin or pinion bearing or sprocket shaft bearing then you have serious issues because you're tolerances are way out of whack and there's no oil that's going to quiet them down..