Oil (Type/Weight)

After much searching, I finally found myself a 1974 Commando Roadster 850 (Frame/Engine/Trans# 307909), a bike I've wanted for a very long time. I'm going to tune it up this weekend and have been searching through the site for information regarding the type (dino/synth/semi) and weight of oil I should be using to change the crankcase and transmission oils -- fortunately, I have a dry belt/clutch conversion and do not need to worry about the primary.

I know this is a source of much debate, but I just wanted to ask a few basic questions:

1) Should I use dino or synthetic in this bike? I would think that regular (frequent) changes with SJ 20W50 in the crankcase would be the way to go. Will I be fine with this, or is there an advantage to synthetic in these bikes? I do not want to blow any seals!

2) 90W in the gearbox? I've never had to oil a motorcycle gearbox before and am not sure if there is also moto-specific oil for these, akin to the SJ rating for regular oil.

3) Is there a part number for a FRAM (or other universal) oil filter to fit the 850 Commando?

Thanks for your help!

When going to synthetic, you will notice oil leaks you never had before. I'd stick with regular oil unless you want to be chasing leaks.

After a discussion with the owner of Web Camshafts, I stay away from synthetics for the engine. I use Torco MPZ. It has a high zinc content that a lot of the modern oil lack. Zinc seems to be what our camshafts need.

Some of the synthetic gear lubes have advanced anti-shock properties. I, personally, don't use synthetic in the gearbox. It doesn't seem to require anything other than a petro based lube.

Thanks for the responses. A few followups:

1) Do I go with a dino monograde (20W) or a dino multigrade SJ (20W-50) in the crankcase?

2) Do I go with 80W or 90W dino in the gearbox?

The gearbox oil should be "EP" 90W "EP" stands for Extreme Pressure and is intended for gear lubrification.

The engine, I use Castrol 20W-50, works OK. The main advantage to syntetic oils is fewer oil changes, I think it's better to change the oil more often, at the end, it comes down to the same price wise. Change less often but more expensive or change more often for a cheaper price.

The oil filter is (I think) non standard as far as North America goes, I know I used to buy Renault filters way back when and they fitted just fine at a fraction of the cost of the regular Norton filters.

Jean

I use AMSOIL manual trans/transaxle lube . It's 75w-90 and is GL-4 rated . I've heard that the GL-5 lubes can be corrosive to"yellow" metals , like brass and bronze bushings .

To me the main advantage of a synthetic in a Norton is its resistance to heat, and a good one like Redline also resists losing viscosity rateing in the roller bearings. Out here in CA when it is hot you can bring non synthetic oil up to carbonizing with these finless jugs.
That said there is no reason you couldn't use any oil you want and just add a good synthetic if you planned to go on a trip that would really get it hot.
In my Goldwings I use Rotella which has no challenge in a water cooled engine. I also use Rotella in the Changs as I don't get them all that hot.

I actually live in Los Angeles. Assuming there is consensus that synthetics will not cause all the oil to fall out of my motor, what weight of oil do you use?

Here you go, read this:

http://www.nortonclub.com/docs/OilTemp.pdf

I am sure it's been posted on here many times previously.

That's a well done article (joke) and is a lot more scientific than my spit on the fins technique. When I got my Nortons hot I noticed carbonizing with dino oil if I tore them down after. When they got hot the oil pressure dropped a lot.
I've blown up two Norton engines, oil was a factor I'm sure in one of them. One blew up shortly after I missed a shift so that was probably me.
By the same token I use Redline 20-60 if I remember the numbers right, the bottle is home in the garage. My bike does not hold much oil and I'd like to have it carbonize as high as possible.
On my last Commando I was running a lot of oil (over 4 quarts if I recall) and when it ran through the frame and big alloy tank it cooled quite a bit. I don't recall the numbers now, but my oil pressure was several pounds higher on an extended freeway trip than with the stock tank.

thought i should share this, i read alot on the suzuki GS forum which is a wealth of info. Most guys on there run Rotella Diesel oil with has a very high ZINC content with is what JimC posted and the most critical point being the camshafts. Whats so great about the Rotella Diesel is its available at Walmart and its CHEAP!!

ludwig said:

I use full synthetic Red Line 20W50 in the engine and Castrol MTX 75W140 in the gearbox , also full synthetic . and Coco , I have NO oil leaks , nada , not even the slightest sweating (and I don't use an anti return valve either ) Oil consuption is neglible : about 0.5 liter (quart) in 5000 km . Oil changes every 5000 km .

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When I went to Mobil 1, when I had my Porsche I noticed leaks that I never had before, like the cam shaft seals and oil pan. The Porsche mechanic I went to even told me that before I switched to syntheic. I'm not the only one to experience this.

Sounds like your motor is tight. Mine wasn't bad and now that the 850 lump is rebuilt I should be totally leak free.

When synthetic oil came out leaks were common. Synths tend to wash away deposits. All the new blends have seal swellers in them due to this problem.
My BMW M Roadster and a lot of Corvettes came with synthetic oil. If they did not use a synthetic they would have had to add an oil cooler. There is a reason my car has an oil temperture gauge.
You can go over to Bobistheoilguy and read about oils for hours if you have the patience.
I used to use Mobil 1 in everything (so I could just stock one type) but now I go with appropriate oil for the use the vehicle gets.

If you don't care for your current camshaft, run Mobil 1.

My 72 Combat would reach oil temps of 240°F in the tank when running hard. I spoke at length with a Spectro engineer. He said that was too hot, considering where the temp was taken. I've since added an oil cooler and the temp usually stays below 200°F. He also warned about too cool of oil. I installed a thermostat. If you run an oil pressure gauge you will notice when the oil gets hot the pressure drop to 2-3 psi at idle. I would guess the oil is pretty thin when hot. Considering that camshaft lobe lubrication in a Commando is somewhat lacking, I think keeping the oil at proper temp is crucial to camshaft longevity.

Thank you all. Now I'm totally confused! ;-)

Let's try it this way. What oil do you use in your Commando? Right now I'm planning to pick up the following:

1) Red Line 20W-50 Synthetic for Crankcase

2) Red Line 90W Synthetic for Gearbox

I plan to change the crankcase oil every 2500 miles.

JimC said:

I installed a thermostat.

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Hey JinC, I'm curious as to what type of thermostat you use and where/how it is installed.

A lot of oil coolers come with a thermostat. It is usually in the intake line and opens when the oil heats up enough.

I really don't know how much ambient temperature affects oil temperature. Does a 20° increase in ambient temp equate to a 20° increase in oil temp? I know I would not run with out an oil cooler and thermostat regardless where I lived. I used to live in Minnesota and saw temperatures in excess of 100°F. I think running on any hot day (+80°) without a cooler can cook the oil. It only takes once to have some serious damage.

Oil choices have a lot to do with personal preference and anecdotal evidence. Bob Raber, of Raber's Parts Mart, swears by Torco MPZ. Good enough for me. I do think Redline synthetic is a superior synthetic lube. I wouldn't even consider using Mobil 1. It may be o.k. for some vehicle apps, but definitely not a Commando.

A little story about oil. I had the oil changed by a quickie lube joint some years ago in my Dodge Durango. The idiot doing the oil change never put in the drain plug. I drove off. Got about a block away and every light came on and bells sounded off. I drove back to the oil change place. They put in the drain plug and filled it up. That was at 75,000 miles. I now have 104,000 miles on it. Still has 60 psi oil pressure and uses no oil. The Durango always had Castrol synthetic. Needless to say, I still use Castrol synthetic in the Durango .

I think it all adds up. If 20 degrees is going to be the difference between oil failure and a nice run it makes a difference.
I think freeway cruising to get the oil hot and then getting stuck in traffic makes my bikes act the hottest.
Running in Maine I never really had those conditions but here in the Bay Area I can get them all summer.
By the way Bob Raber is a nice guy and he has figured out what works well for him. I'm sure there are a number of good products out there, the choice we have now is amazing. I used to have to use airplane oil when I was a kid as I couldn't get anything else.

Personal experience only.

In my old air-cooled VW Formula Vee race motor I always ran synthetic's because it would withstand the constant 100°C plus and occasional 120°C temperatures without degrading. The oil that everyone in my class used was Belray EXS, a 10w/50.

My norton doesn't see those kinds of temperatures so I stick with dino oils.
I tried Valvoline XLD 20w/50 for older engines and that seemed fine.
I am currently running Penrite Enduro which is a 25w/70 and the bike runs a little quieter. I also noted that it has a very high zinc content.

In the Norton gearbox I was running Redline Heavy Duty Shockproof but after about 2000 miles I thought I had struck gold when I drained it. There was a good tablespoon of gold flakes laying in the bottom of the gearbox, plus what was floating around in the oil.
I am now using Castrol EPX90 and have only completed about 400 miles on it so have not tested it yet.