Does anyone have evidence that GL-5 doesn't attack brass?

Would love to use GL-5 oil in my gearbox but I have heard many times that they attack brass. Any thoughts.

Yes, I posted a link recently to a bush manufacturers design engineers guide. It states that GL5 is good as long as the temp of the oil does not go above 100C, as its a separate gearbox badly prone to water in the oil you can safely say use GL5. As I have never used anything else but GL5 in any gearbox and have had no issues with dissappearing bronze bushes thats another myth debunked.

I forget the numbers but I use Royal Purple in a lot of equipment.
After calling and assureing myself that it did not harm red metals I tried it several years ago.
This is mostly commercila equipment I know I'm going to ignore but I use it in my bike gearboxes also. It's more expensive but I get good results, usually better shifting, and I've never had to tear one down. No it is not harmful to seals.
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I've been using GL5 for years. Pre-internet, I wasn't aware of the situation. I have never seen problems with the bronze.

Current oil product prices mean that all of them have a damaging effect on the brass in my pocket.

I too would love to be convinced, but 100 degrees centigrade is only 212 degrees fahrenheit (?) I could see cases heating gearlube up to that point during a hot run...no?

Believe me, I wanna be convinced!!!

Cookie - hi. Royal Purple is GL-4 I believe. That's what I've been using pending confirmation that GL-5 is okay - in which case I'll happily switch to Redline Shockproof gear lube (nothing wrong with the Royal Purple, I'm just a big Redline fan).

I think it replaces 4 or 5.

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BrianK said:

Cookie - hi. Royal Purple is GL-4 I believe. That's what I've been using pending confirmation that GL-5 is okay - in which case I'll happily switch to Redline Shockproof gear lube (nothing wrong with the Royal Purple, I'm just a big Redline fan).

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I used Redline Heavy Duty Shockproof. After little more than 1000 miles using it I cleaned more than a tablespoon of gold flakes out of my gearbox.
I don't know if it was the Redline's fault or not but I haven't had the same problem since switching to Castrol EPX (a GL5 oil).

Veefore, good to know (if not to hear!). Think I'll hold off on the GL5 for now....

There is a lot of difference between Redline and Royal Purple.
Castrol has traditionally made good stuff too. Let us know how that works out for you long term.

BrianK said:

I too would love to be convinced, but 100 degrees centigrade is only 212 degrees fahrenheit (?) I could see cases heating gearlube up to that point during a hot run...no?

Believe me, I wanna be convinced!!!

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Not much chance in NW Europe I suspect.

I pulled off my gearbox outer cover tonight because it was dribbling from the gasket. Judging by the condensation damage above the oil level, there's no way that box has been above boiling point.

I change my oil every 1000 miles but this doesn't seem to help much. It's been about five years since I had the box apart. The pawl spring was worn about half through so I think that I might be pulling the outer cover off when I oil change in future.

veefore,you're probably correct the oil isn't resonsible for your gold strike ,more likely the sleeve gear bush finally slipped all the way out and now has no more left to grind away.Are synthetic oils better or worse at protecting the gearbox from condensation damge?I had heard that they dont protect against rust as well

That's interesting Splatt. I've never given condensation protection much thought as I really don't see much of it.
The bikes I have most likely to get water in are my Changs, if you let the speedo seal get bad water can leak in. I have Royal Purple in there and at this rate it looks like I may die before I tear my everyday one down. I may never find out!

ludwig said:

79x100 : gear box oil change every 1000 mls ???
How often do you change the oil in the gearbox of your car ?
I only change the oil when I have to do somethng in the box , like changing an oil seal ore something . Maybe every 10 - 20000 km .
What's so special about the gears of a Norton that they need fresh oil every 1000 mls ?
On a 3000 mls holiday trip that would mean 2 oil changes ...not very practical !

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Ludwig, I could give you a smart-arse answer and say that I just like watching oil dribble down the main stand spring. Truth to tell, there are probably lots of reasons, most of them stemming from paranoia and a need for reassurance that developed during my early days of Commando ownership. I rather look on the oil as a sort of sacrificial offering intended to keep me in favour with the old and vengeful gods who seem to have responsibility for those who fiddle with old motorcycles.

I'm not pedantic about mileage on holidays on the basis that the time interval is short, reducing the chance of condensation and the locally available oil is not likely to be my first choice.

My 850 came with an extra stellite cam follower foot floating around inside it and I then fitted a soft cam so I got into the habit of constantly watching the drain plug for particles and performing post-mortems on oil filters. It then seemed a bit penny pinching not to drain the gearbox whilst I was lying on my back with warm oil running down my sleeve.

I also replace brake fluid and fork oil every year and I wouldn't do that with a car either. With the Norton, I regard anything that I can do to reduce the possibility of wear or damage to be well worth doing.

I tend to agree with 79 that the Norton gods seem to demand extra-copious amounts of appeasing via sacrifices of virgin oils of various sorts....