I'm sticking with ATF or its thin synthetic relatives for surprising sports bikes in lower gears for most of an hour a go in Ms Peel but plain Jane Trixie gets the standard thick modern lubes that don't eat bronze bushes anymore. Even gear box lube should be changed out after run in, and time to time renewed d/t chemistry corrosives - though less prone that engine oil. Here's a primer on little discussed issue that may be a main reason surfaces go weak to rub away too fast.
http://www.mattituck.com/articles/engcorr.htm

I mostly use diesel grade oil in all my engines, mowers to motorcycles to truck. The zinc/phosphorous is about right, if ya can get the oil hot enough for those to adhere to surfaces and cook off moisture, while maintaining oil pressure. Commandos used to win endurance races - so rate your mechanical manhood by that eh. I'm not feeling very matured yet myself ok.

Sure glad this subject got brought up again so I can get all paranoid once more......

I've got about 45,000 miles on this speedo, more on the engine and transmission. No racing, but it is hard not to wind on the throttle to get that buzz that comes on after 4000 rpm. Quite a few miles were on 10W40 Valvoline and lately I've been using 20W50 Rotella. The gear box gets what ever 90W that goes in the H. Last summer I rode more or less 3700 miles to the INOA rally. If you did ride there, you know that some of the days were very hot on the way home. What more do you want out of an old bike ?

Your results may differ, but I still believe that you are over thinking this. Ride your bike. Change the oil(s). Fix it when it is broke. Repeat.

Greg

Wow Greg, my respects on such a long hot ride and bravery to use off the shelf oil a long time. I so want to have similar story - someday - maybe - please.
Spent last decade.2 learning downsides of Commandos and lubes, maybe, just maybe, next time out a charm?

gjr wrote:I've got about 45,000 miles on this speedo, more on the engine and transmission. No racing, but it is hard not to wind on the throttle to get that buzz that comes on after 4000 rpm. Quite a few miles were on 10W40 Valvoline and lately I've been using 20W50 Rotella. The gear box gets what ever 90W that goes in the H. Last summer I rode more or less 3700 miles to the INOA rally. If you did ride there, you know that some of the days were very hot on the way home. What more do you want out of an old bike ?

Your results may differ, but I still believe that you are over thinking this. Ride your bike. Change the oil(s). Fix it when it is broke. Repeat.

Greg

Agreed. Using a Valvoline 90W syn with no issues. I change it out every year or two due to storage and moisture in these parts. So Greg, was it as hot as Utah? Going to New York?

Hi folks. Don't get too hung up about "GL-5". The American Petroleum Institute (API) has defined the performance requirements for the majority of lubricants in common use. There are two primary specifications for gear (G) lube (L) which are GL-4 and GL-5 with GL-5 having the higher performance criteria. I would suspect the brand and not the spec. Had an interesting conversation with an engineer from a major synthetic oil manufacturer. I wanted to use their oil in my, then new, R1150. My owners manual (Canada) clearly specified not to use synthetic oil and the on line manual (USA) clearly specified not to use Mineral oil. His bottom line was that the base oil in any brand name lubricant was far less important than the chemistry of the additive packages. He also advised not to change to synthetic in older engines unless it was freshly rebuilt. End result - I stuck with dino oil for Canadian warranty reasons. Over the past 45 years I have personally used mainly Castrol, Shell and Gulf oils in my cars, bikes and boats and have yet to have a lubricant related failure. For what it is worth, synthetic oils, in general are less able than dino oils to emulsify water and keep it in suspension so I will never use a synthetic in a non-unit engine myself unless specified by the manufacturer. Sorry if this sounds like a rant. BTW, saw this on a Ducati website a few years ago;"If it makes you feel better to by expensive oil, go ahead. Otherwise it is perfectly ok to use what the manual calls for."

Anecdotal personal experience: I've used Mobil 1 Synthetic Gear Oil in my gearboxes for years. One gearbox is in my street Commando, the other in the Manx which is only used on the track. I have had one gearbox failure on the Manx, that being due to failure of the sleeve gear bushing which became galled to the point of almost seizing up (coming off the track I thought the brakes were binding). Looked like a lubrication failure to me. The bushing looked as if it had run dry despite the box being properly filled. Several paddock advisors (much like Navy Sea Lawyers), indicated that I should never use Gear Oil in a Norton gearbox, it being too thick to adequately lubricate the sleeve gear bushing. I've had no failures in my street gearbox.

One of my racing friends who runs a brace of Manx's runs ATF. However, I've seen him experience at least two gearbox failures, with one of those boxes being of the very expensive six speed variety. I think it difficult to attribute the failures to lubrication, but I'm still not comfortable running something that thin.

Okkie Dokie then that settles the issue Steve, period, done, throw in the ole towel on it, there is no way any liquid lube can get into the sleeve bushes when spun up as they are above oil level and sling out any lube trying to get in. If any place in Norton needs a pressure feed this is it. Your report backs up my experience, > to give some idea how much fun I had on my street bike running away from hot shots where it mattered most. Cog wise 3rd seems to be my weak set or teeth.

On Ms Peel I will have the surfaces cryogentic'd, dry friction coated, run ATF and replace at first hint of clutch basket wobble.

MexicoMike wrote:Hmm, makes one wonder how Norton Commandos ran for many thousands of miles originally when there was no such thing as synthetic oil and they were generally ridden a lot harder by us young guys than they generally are now by us old guys...

I thoroughly agree.