Oil

[Sgriger534]

i was just wondering what kind of oil to use for the middle gear and final drive

[dbeardslee]

80/90 synthetic hypoid gear oil.

[XSokieSPECIAL]

80/90 is what it calls for, however, the higher quality gear lubricants were not available when this bike was built or when the manual was written.

I found that 75/140 Royal Purple synthetic gear lube greatly reduces gear noise from the middle drive and final drive.

I wish I could find a way to do the same with the transmission without causing clutch problems.

IMHO

[Sgriger534]

what kind of oil do you use in your transmission

[dbeardslee]

Okie - does the Royal Purple have a hypoid additive in it? Royal Purple - sounds vaguely like some stuff I ran across in the 70's . The tranny is lubricated with the same oil that lubes the engine. I prefer 20/50 dyno changed every 2k miles. That's also why you never want to tow an XS. When the motor isn't running it isn't pumping oil to the tranny, and you can destroy it by towing. Just thought I'd throw that little tidbit out there.

[XSokieSPECIAL]

what kind of oil do you use in your transmission

The transmission and clutch run in the same oil sump as the engine. I'm sure the engine wouldn't have a problem with the synthetic but the clutch would have some slippage issues with it I believe.

If anyone knows anything different I'd like to know.

[CatatonicBug]

what kind of oil do you use in your transmission

Next to tires, that is the question that causes the most debate around here. Basically, pick your favorite brand of oil, and use something in the area of 20w50. The main thing to watch for is the symbol on the back of the carton, and avoid using oil with this symbol:



The one you want will not have the "Energy Conserving" part in it. Like this one:



Most people avoid using synthetic oil, as it has been reported to cause clutch slippage, but others use it without issue. Try an oil, and if you don't like it, try something else with the next oil change.

[XSokieSPECIAL]

Okie - does the Royal Purple have a hypoid additive in it? Royal Purple - sounds vaguely like some stuff I ran across in the 70's . The tranny is lubricated with the same oil that lubes the engine. I prefer 20/50 dyno changed every 2k miles. That's also why you never want to tow an XS. When the motor isn't running it isn't pumping oil to the tranny, and you can destroy it by towing. Just thought I'd throw that little tidbit out there.

Royal Purple is just a brand name. What I am putting forward is the 75/140 synthetic gear oil. Nearly all the newer Ford trucks use it in thier diffs, if you put anything else in there and they get noisy as hell.

I use Castrol 20w50 4 stroke MC oil in my engine also. I was using Rotella 15w40 when I first got my bike but had BAD clutch slippage with that because of the friction modifiers in it. Changed to the afore mentioned Castrol and the slipping went away.

I would like to find a lighter/heavier weight of synthetic to run in the crankcase that wouldn't cause clutch problems. The synthetic IS a superior gear and engine lubricant but these old wet clutches don't like it.

[yamahansolo]

i have used several synths with no issues as long as it doesn't say "energy conserving" like the label above. synthetic oil just lasts longer it's not slicker.
i am using 80w90 synth in my middle and final gears i changed them 3 weeks ago with no problems.
i just rode to pensacola from north ga yesterday for an outlaw visit. i mean inlaw... this bike is awesome! i am using 20w50 oil and recently i found a bottle of synth that contains high amounts of zinc!!! i only added a tiny bit though. i need to drain and re oil with this stuff.
any way 400 miles and my 79 doesn't even burn an ounce of oil. it's still full. who says old bikes are tired and worn out??? i was running 80-90mph the whole way. no problems at all... except the 37 mpg instead of 39 to 40 i usually get.... also there were a couple of blips of the throttle ito triples... justfor fun. good thing i didn't hit a deer!!!

[XSokieSPECIAL]

What kind of synth motor oil are you running Chris?

[Rickrod3]

Royal Purple is just a brand name. What I am putting forward is the 75/140 synthetic gear oil. Nearly all the newer Ford trucks use it in thier diffs, if you put anything else in there and they get noisy as hell.

I use Castrol 20w50 4 stroke MC oil in my engine also. I was using Rotella 15w40 when I first got my bike but had BAD clutch slippage with that because of the friction modifiers in it. Changed to the afore mentioned Castrol and the slipping went away.

I would like to find a lighter/heavier weight of synthetic to run in the crankcase that wouldn't cause clutch problems. The synthetic IS a superior gear and engine lubricant but these old wet clutches don't like it.

Is that the 4T oil from castrol?

[yamahansolo]

it's valvoline racing 20w50 in a black bottle it has zinc... it's not for bikes but you can use it because it's not energy conserving or whatever... i have used many diff car oils in the past. rottella used to be good because it had zinc but they stopped adding it..
the racing oil says it's good for flat tappet cams on the back i bought it at az for 8 bucks...

[XSokieSPECIAL]

Is that the 4T oil from castrol?

Yup...thats the stuff.

[Welsh1100]

Oil

It is my understanding that running synthetic oil in older bikes may not provide much more benefit over conventional oils. I run Castrol GTX 20-50 in my '79f standard.
I have heard that if deciding to run synthetic oil...one should thoroughly flush the crankcase and install a new filter. After running about 500 miles...install another new filter and moniter oil level.
There is nothing wrong with synthetics in my opinion. However...they can't be blended with conventional oils. Should one find oneself out in the proverbial "boonies" and require a "top off" the desired grade of synth may be unavailable at the old, one pump gas station.

[CatatonicBug]

However...they can't be blended with conventional oils.

That's not entirely true. There is no need to "flush" the system when switching between them, but it's probably a good idea not to "top off" with a different type. It's not like brake fluid, where there will be a reaction between the 2 types (Dot3-4/Dot5).