synthetic oil (again)

Has any research concluded definitively whether modern synthetic oils are better or worse for old motorcycle engines? i.e. my '71 Commando. Morris will of course tell you their Golden Film Classic Oil specially formulated for older engines is best (and it's what I use), but is it? Or is this one of those topics about which there are zillions of opinions, but no evidentiary based data?

The molecules are smaller so there are more drippages on the laneway.

Air cooled engines that occasionally get stuck in traffic jams are a great application for synthetic oil. :idea: JMWO :mrgreen:

The molecules are smaller so there are more drippages on the laneway.

Click to expand...

ha, good one!

touche, and because older engines have bigger motor clearances therefore they need bigger molecules to fill those spaces,ie ...non synthetic oil !

fun game!

The very best oil is quality clean oil! Change often. :wink:

Anything with a poetic name like "Golden Film Classic Oil" must be bloody fantastic!

You engine will last forever, with a golden film classically oiling all the moving parts.

There can't be any doubt that synthetic is 'better'.

The question is, do you need that 'betterness'?!

If you only do a few hundred miles a year and never go over 3,000rpm then literally any oil will do if it's clean and changed anually.

If you do Iron Butt mileage and / or thrash the living daylights out of it every day, then you need all the help you can get, and synthetic would be a wise 'insurance'.

Generally speaking, synthetic oil retains its molecular structure at a higher temperature, lubricates better at a lower temperature, lasts longer and has higher film strength and lubricity.

But having said all that, a top end mineral oil will outpform a cheapo synthetic brand.

Personally I use Red Line synthetic. But as others have said, for most low mileage 'non boy racer' classic riders, any oil will be fine so long as it's changed regularly.

I prefer the extra protection. I have used Amsoil for many years. A little too pricey
I now use Valvoline VR1 as a good compromise.

Good feedback, guys. Some of it pleasantly droll. No research data, which I guessed was the case. However, assumptions based on knowledge of what makes a synthetic better indicates zero risk and some benefits in using it. I can and will push my hot rod Commando to redline because, well, it's fun and the symphony of those pea shooters at high revs... Time to drain the luxurious sounding Golden Film and put in some quality synthetic.

Tangozulu said:

Good feedback, guys. Some of it pleasantly droll. No research data, which I guessed was the case. However, assumptions based on knowledge of what makes a synthetic better indicates zero risk and some benefits in using it. I can and will push my hot rod Commando to redline because, well, it's fun and the symphony of those pea shooters at high revs... Time to drain the luxurious sounding Golden Film and put in some quality synthetic.

Click to expand...

+1 for your approach to how to ride a Norton AND oil...

Remember these motors need zinc (ZDDP) for the cam and followers. Modern engines don't need zinc and, in fact, can't have it in the oil as it's bad for cats.

So, don't be fooled into thinking "if it's good enough for Porsche/ Mecerdes/ Aston Martin then its plenty good enough for a Commando" cos it ain't so!

Redline has one of the best additive packs and highest zinc content out there... IF you buy their motorcycle oil. I use their 20/60.

Their gear oil is awesome too. I use their lightweight shockproof, its alien green and sticks like sh*t to everything!

Fast Eddie said:

+1 for your approach to how to ride a Norton AND oil...

Remember these motors need zinc (ZDDP) for the cam and followers. Modern engines don't need zinc and, in fact, can't have it in the oil as it's bad for cats.

So, don't be fooled into thinking "if it's good enough for Porsche/ Mecerdes/ Aston Martin then its plenty good enough for a Commando" cos it ain't so!

Redline has one of the best additive packs and highest zinc content out there... IF you buy their motorcycle oil. I use their 20/60.

Their gear oil is awesome too. I use their lightweight shockproof, its alien green and sticks like sh*t to everything!

Click to expand...

The thing to remember is that you have a hot aircooled motor. The thinner viscosity multi-grade synthetics are formulated for water cooled engines. News from the air cooled dirt trackers is that using synthetics can result in piston/cylinder scuffing - probably due to thinner multigrades.

So Fast Eddie is giving good advice when recommending the heavy side 20/60 weight Redline.

One thing I learned from an Aeronautics teacher is that too many additives will actually reduce the ratio of the oil that does the real lubricating. The ingredient that makes an oil a multigrade is not a lubricant. This is why straight grade oils can protect better than multigrades. You just have to use common sense and warm up the motor before thrashing it. My personal preference is Amsoil (dominator 15/50 weight) mixed half and half with a high quality oil like Vavoline 50 wt straight grade oil racing oil (40 wt in winter) - and I generally use a higher percent of straight grade than synthetic. The high tech additives in synthetics have great value - you just don't want more of them than necessary, and that stuff is expensive.

I'm not seeing any appreciable cylinder wear, only some ring ridge wear near the top of the cylinder after many many miles as observed in previous rebuilds.

For those who are too lazy to mix - there is Spectro golden 20-50 semi synthetic oil. Other promising oils to look at are Aircraft piston engine oil and oil designed for air cooled Harleys.

Wondering about using aero oi. Those engines are laregly low compression, low rpm, steady throttle opening and low output
per size of engine all rather unlike a motorbike engine.

I thrash my bike from cold all year round and have done so for the last 8 years with cheapo Tesco 5W-40, and strangely the lump is still in one piece with little debris on the magnetic plug. I can be cruel to my ride as some may know repairing it is not an issue for me.

It might be the fact that I thrash it, that causes plenty of oil to distributed around the engine, one day I'll grow up and slow down.

I use Valvolene 4T dino motocycle oil in 20w/50 in all of my bikes. Meets all manufacturers spec and is 1/2 the price of their equivalent synthetic product. Change it every season which is usually around a 1000 miles per bike. Changing this frequently in low mileage bikes is mainly to remove combustion byproducts, acids and moisture. Always riding the bike at least 10 miles or until its good and warmed up helps cut down on the build up. See no point in paying the premium for synthetics unless you ride high mileage. Only exception is the Sportster which started out on Harley Synthetic 20w/50 and has stayed that way and does 5000 miles between changes.
This is a good article on oil contamination. Note especially the section on soot and carbon. Older engines without fuel injection often run rich on one of the carb circuits, often the idle circuit. The black color oil takes on is from the carbon. My mantra is use the less costly alternative and change more often to get the crap out.
http://blog.amsoil.com/how-does-motor-o ... ntaminated

Appropriate oils,for appropriate engines. If racing,I would use a caster based oil,such as R40. If using on the road,a good quality 20w50,preferably m ineral,changed once a year or every 3000 miles.
I run a Triumph Dolomite Sprint on the road,and always use 20w 50 mineral oil.
I race a Yamaha TZ750 sidecar (have done for 10 years) and use only caster based Castrol 747.Wont use synthetic in either.(£12000-£15000,these days for a TZ engine).
However,I would not dream of using either in a modern vehicle,such as my dialy driver.
Modern synthetic oils are formulated with modern vehicles in mind,and as such are thiner for the closer clearnances run in new engines,and the majority of which are water cooled.
Norton Commandos are not only air cooled,but oil cooled as well,and this needs to be taken into consideration when selectting an oil.

The big problem with multigrades in Commando engines is the very high piston velocity.. breaks down the additive package.. whether synthetics are more resistant to that I do not know... Incidentally it takes quite some distance to bring an unfaired Commando's oil upto working temp. 10 to 15 miles in heavy traffic ...

Well worth reading up about the multigrade topic on Redlines web site. They do NOT use the additives used by most to achieve this. Can't remember the details now, but I researched long and hard some while ago when stressing about what oil to use and was 100% convinced by Redline. Been using it ever since.

FWIW................

72,000 + miles on my 1975 Commando, no leaks, zero, none. I use Mobile 1, 20-50 V-Twin, it has all the additives required per John Favill.
Riding style varies but on most of my long rides, 10 INOA Rallys, the bike went loaded down like a pack mule, heat and cold, like last July's ride to Buena Vista VA, and back to the North Shore of MA.

Fast Eddie said:

Well worth reading up about the multigrade topic on Redlines web site. They do NOT use the additives used by most to achieve this. Can't remember the details now, but I researched long and hard some while ago when stressing about what oil to use and was 100% convinced by Redline. Been using it ever since.

Click to expand...

Eddie , which of their gear oils do you use? the 20 /60 sounds good to me and am going to break the habit of a lifetime and change from monogrades.

oldmikew said:

Fast Eddie said:

Well worth reading up about the multigrade topic on Redlines web site. They do NOT use the additives used by most to achieve this. Can't remember the details now, but I researched long and hard some while ago when stressing about what oil to use and was 100% convinced by Redline. Been using it ever since.

Click to expand...

Eddie , which of their gear oils do you use? the 20 /60 sounds good to me and am going to break the habit of a lifetime and change from monogrades.

Click to expand...

Somewhere on their web site they explain that their oil is not actually a multigrade, but it behaves like such due to the quality ester base stock they use. I personally believe our old engines benefit from the thicker stuff. I dynod a hot triple motor once to test thick and thin oils and could not detect any difference, so I don't see any advantage to putting thin stuff in our old relics.

Regarding gear oil, I use their middle one "lightweight shockproof" they also do a "superlight" which is used by many classic and vintage race boys (I used to use this, but as per the above, I now prefer it a tad thicker). They do a "heavyweight" too, but this is for seriously stressed situations like top fuel dragsters etc.

They say this about their lightweight shockproof "lightweight Film thickness greater than an SAE 75W140, yet low fluid friction like 80W gear oil or 30W motor oil".

I recently had to strip the box on my T120, I had just put some of this stuff in the bloody thing. It gets everywhere and sticks like the proverbial to everything, everywhere, which has to be a good thing in my book.