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Synthetic Oil

32K views 60 replies 23 participants last post by  RetroRod 
#1 ·
I am completing a bottom up rebuild on a '76 T140 and after having cleaned the sludge trap I am thinking that the stuff removed from there can't be a good thing. Surprisingly, I couldn't find any history of of a discussion on the use of synthetic oil.

I was wondering what if any experience and comments you might have on going synthetic in one of these old classics? They actually seem to recommend synthetic in the new Triumphs. Anyway, I already have an oil filter installed. I did some reading to discover that not all synthetics are the same. Actually, it was pretty interesting reading with several articles claiming Amzoil exceeds everyone else's performance including that real pricey Harley Davidson oil. They claim better oil pressure, viscosity and corrosion protection, as well as, less sheer and scarring. Just so you won't think this is a sales pitch, I won't post any links Although some naysayers warn about clutch slippage, I don't think it should a problem as I've used automatic transmission fluid in the primary and the clutch worked like a charm. There's nothing much more slippery than tranny fluid. I hope to defeat any oil seepage by switching to an improved gasket compound.

This do or don't discussion has been a hot topic in the general automotive world. I can still be swayed...
 
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#2 ·
You're going to get both sides on this one. If you like synthetics, use them, but unless you've stopped up the three transfer holes in the crankcase and installed a crank seal in the left case, your engine oil and primary oil are shared on your bike. If you put ATF in the primary it eventually was replaced by oil from the resevoir. If you use synthetics, don't use the extra slippery stuff or your clutch will slip because the engine oil is shared with the primary.
 
#3 ·
I tried synthetic a few years ago.
I'm convinced that's when my first leaks started since the Bonne was new in '76.
Same thing on my '89 BMW auto; leaked past the seals like a fountain.
Now my thoughts are if the manual doesn't suggest it, don't mess with a good thing.

Let us know how it goes.
 
#4 ·
Hi Thirdbike, as Beemie says......... use a good quality SAE 20/50 mineral oil and the ATF in the clutch. DO NOT over fill the primary, better to have 1/2 ounce less than too much. While there might, perhaps be a small transfer over time, don't worry about it. More importantly, get a motorcycle specific engine oil if you can. I would recommend a 70/90 semi synthetic for the gearbox.
Roy.
 
#7 ·
I am really curious now why everybody so far is set against using synthetic. Other than the leakage potential what else nixes this switch? I was talking to a buddy who used to race stock cars. He says his engine (the coolant) ran 15 degrees cooler with synthetic and runs it in all his 4 wheeled vehicles and his new Kawi.
 
#8 ·
Not against synthetic if the vehicle seals were designed for it.

But then again, even some of those suffer; our vette's rings never seated; It came with Mobil 1 from the factory.
Apparently lubricant can be too slick.

Probably sooner or later we'll have a limited supply of dino and the synthetic will cost less and the tides will shift.
 
#10 ·
Firstly, GOOD advice from GPZ. You won't go far wrong with Castrol GTX 20/50. Next, Germ, Cheap is not always bad......... there are some good cheap oils out there. Look for one with an API SH or better. If it's cheap, change it more often.............. Oil does not break down, it gets contaminated.
So, on that theme of contamination, using a synthetic on our old engines with large tolerances, air cooled and often not equally air cooled, blow by from pistons, valve guides, etc. do not work. They were designed in the 1940's and the engineering is from that period.
Mecchanica will tell you other wise and I believe what he says. However what he does not tell you is how well he prepares a motor or the time spent measuring and generally blue printing......... THIS IS the secret. Running an old engine on new synthetic oil will not give good results. Honest, oh yeah and it is VERY EXPENSIVE.
Roy.
 
#11 ·
The spec for my T140 ('79 model) is 20W-50. Castrol GTX is mentioned by name. It may have been 20W-50 when the manual was written, but it isnt now. Unless it is different in the US, Castrol GTX is 10W-40 or 15W-40 depending upon the precise version of the oil; http://www.castrol.com/castrol/sectiongenericarticle.do?categoryId=9014101&contentId=7027413

Castrol do make a 20/50, it is called XL 20W-50; http://www.castrol.com/castrol/sectiongenericarticle.do?categoryId=9014107&contentId=7027099#7094382
 
#13 · (Edited)
Thanks Dagad and I appreciate your thoughts,

I hear what you are saying. I have always used Castrol GTX. However, some of your arguments actually favor the synthetic route. Synthetic is available in a 20/50 blend. Being of the same viscosity the larger tolerances should not come into the equation. In fact, if the engine was of a newer vintage with tighter tolerances, we'd need to go to a much lower viscosity like the 5/20 formulation used in Honda cars etc.

Synthetic actually withstands higher heat before breaking down and yes because of the high heat from the air cooled engine there is a risk of oil breakdown. Chemically, synthetic is more uniform and more stable. It has uniform sized long chain molecules and so lubrication is much more uniform. Because dino oil is a petro-carbon based product, it readily re-combines with contaminants introduced into the oil in the form of carbon, blow by, gasoline and dirt. Synthetic, on the other hand is "incompatable" with these petro-carbon based contaminants and so these contaminants are held in suspension rather than solution. This does, of course, necessitate the need for a good oil filter to remove these contaminants. The overall result is being and biggest benefit to using synthetic is that engine wear is significantly reduced.

The only negative that I am sold on is the high cost of a premium synthetic. Somehow, I can't help getting the sense that what I am hearing is the same arguments used to reject synthetic oil for cars when it was introduced some years back.

Oh by the way, Castrol does provide in North America Castrol GTX with a SAE 20W-50 viscosity and rated API Service SM
 
#14 · (Edited)
I largely agree with Dagad, but a little more information.
SG is the best rated oil, as it allows for the highest levels of zinc and other additives. However a 20/50 grade oil is excempted from the maximum (0.12%) as it is designated for old engines only ( non efi or catalitic converter) SH/SL allows for 0.10% and from there on it gets worse. Later oils have less and less anti wear additives to protect the efi/catalyst) The zinc (or calcium) is needed in old flat tappet engines, and it is here on the cam lobes and followers that a poor oil will fail. Most modern engines use high flow rates and wetsumps to alleviate this. Mechannica pays particular attention in lightening the loading on the cams and followers. His engines are far from standard. A simpler way to help this weak point is to use tamer cams with silencing ramps. like the old 6T or 5TA profiles. Remember with big ends you need the right pressure to keep them running without rubbing, also the oil cools the bearing so you need the right flow rate. If you change the viscosity you also need to change the flow rate to suit. EG if you use 5/30 oil your pump may have to pass more than double the amount of oil through the bearings to maintain the right pressure. You have to accept they were designed as a complete system. Changing one thing often has unpredictable results elswhere.
 
#15 ·
Please allow me to add one more comment or more accurately a link to a white paper which seems to address many of the concerns raised including the lack of Zinc as reported by Panda.

I am only a consumer, not an engineer and I assure you that I don't make any commisions. I think the paper speaks for itself.

https://www.amsoil.com/lit/g2156.pdf

Again thank you for all your contributions.
 
#16 ·
Please allow me to add one more comment or more accurately a link to a white paper which seems to address many of the concerns raised including the lack of Zinc as reported by Panda.

I am only a consumer, not an engineer and I assure you that I don't make any commisions. I think the paper speaks for itself.

https://www.amsoil.com/lit/g2156.pdf

Again thank you for all your contributions.

That is a good reference.

I wouldn't be surprised if the motorcycle oils were exempt from the zinc restrictions, but that would be subject to change as some bikes are coming through with cats now.
 
#17 ·
If you are still interested

For those that are still interested, I have asked for further information from two of the more known synthetic oil companies. I already have one response and a more technical follow-up is coming from another company. I asked these guys about all of it; blow by, heat, seepage through seals and lubrication. The need for flat tappet engines needing more wear additives than the new restricted SM rating has been commented on. The issue of using synthetic oil in air cooled engines originally designed to run on non detergent oil will also be addressed by their research people.
 
#18 · (Edited)
The Answer

I have now received the answers from the two oil manufacturers regarding using synthetic oil in our old vintage bikes. To begin, the response from the two companies differed somewhat in that one company took the trouble to email me a couple of times before calling me and speaking with me for nearly half an hour. The other sent a more pro-forma email. Synthetic oil and its application is not a cut and dry subject. Obviously, the following is a condensed version of everything I have come to appreciate about the oil products and their application.

There is a big difference between automotive and motorcycle oil. “In 1996 the American Petroleum Institute (API) upgraded the performance standards of automotive oil from SG to SJ (currently SM). This upgrade impacted the friction modifiers and zinc and phosphorus levels, to address the fuel economy, catalytic converter and pollution issues of passenger car owners. For motorcycles, the additional friction modifiers can affect wet clutch performance…”

Motorcycle oils are generally formulated to meet the API SG standard. Motorcycle oils contain higher amounts of wear additives in the form of zinc and phosphorus. This is especially beneficial for flat cam followers. One manufacturer went so far as to say, “API SJ engine oils (automotive type) have a minimal shear stability requirement; therefore, some types may lose their viscosity more quickly when used in a motorcycle, due to the stresses of these bike engines.
There is little doubt that synthetic oil provides better lubrication than petroleum based oil. Synthetic oil creates better “elastohydrodynamic” lubrication –(ain’t my word). This was explained as the oil’s ability to create a full fluid film so that there is no metal to metal contact. At start-up, lubrication (or the lack of it) is critical. Synthetic oil at the lower range has a better “pumpability” than petroleum based oil and so lubrication protection begins sooner.

Synthetic oil is not a uniform product. Some are fully 100% synthetic carry a grade IV rating. Others are what are referred to Hydroisomerized petroleum oils marketed as synthetics under a new law and carry a grade III rating. To further confuse things there are also blended synthetics. In other words, they are a mixture of part petroleum and part synthetic oil.

Let me get to the meat of the matter. The long chain molecules of synthetic oil stand up to wear longer. Shearing and scaring is reduced. The ability to withstand acidification is increased. The Total Base Number (TBN) is a measure of how well oil fights acidification. Synthetics have higher base numbers but not all synthetics are created equal. Obviously acidification is not a good thing but more on this later. While all oil will breakdown over time, synthetic oil withstands this breakdown much better. These issues are especially critical in an air cooled engine. Synthetic oils are more stable over the full heat range. For every 10° C, the reactive rate doubles. Both liquid and air cooled engines run cooler on synthetic. As for wear additives, it is important to remember that these additives are bonded to the base stock hence the same additives combined with an improved base stock translates to improved wear protection.

One area that was of particular interest to me was oil seepage. This issue was described as being “very subjective.” There is nothing in synthetic oil that causes it to seep past gaskets and seals more readily than petroleum based oils on a properly maintained engine as it is somehow thinner or has a lower surface tension. In fact, the viscosity of synthetic oil is more stable over the full heat range. However, if synthetic oil is introduced into an improperly maintained engine including delayed oil changes, acidification has already begun to attack gaskets and seals. Meanwhile the petroleum based oil has begun to “gel” and sludge build-up begins - all of which prevents seepage. Introduce a high quality oil which resists breakdown and voila, a recipe for oil leaks.

If you do not have an oil filter mod and you have not done a rebuild nor cleaned out the sludge trap and you faithfully drop your non-detergent oil after no more than 1000 miles then the benefits to switching to synthetic becomes a less clear. While synthetics provide better lubrication and contain improved wear additives, the introduction of any detergent oil, petroleum or synthetic, could very likely disturb the sludge build-up and as a result may block a critical oil gallery. Without an oil filter there is no way to remove both pre-existing and new contaminants held in suspension. Extending the oil change intervals in these circumstances would (to my mind) be further folly. This leads to a further negative, namely cost.

Many mechanics and experts suggest that oil change intervals should not be extended with synthetic motor oil. Better oil provides better protection within the recommended service cycle. It is argued that extending the change interval defeats this extra protection. Castrol offers a cautionary footnote, “Castrol always recommends that you follow the guidelines of the manufacturer for the GRADE and API specific to your motorcycle’s engine.” On the other hand meanwhile, Amsoil a premium synthetic manufacturer recommends it’s customers they safely can double the recommended factory oil change interval in new motorcycle engines and warranties their product accordingly.

If you really want to know what is going on inside, for $20 you can get an oil analysis emailed back to you within 24 hours of receipt by an independent lab. At the service interval send an oil sample and they'll tell you everything: amount of water, gasket material, boron, sodium, phosphorus, zinc, oxygen, nitrogen, fuel, anti-freeze and the list goes on. In other words; is it safe to extend the oil change interval with a premium product or is it time to consider a engine rebuild.

In summary, you get what you pay for although more reasonable pricing wouldn't hurt. If you’d like your Bonnie to be around another 50 years you have to give it some thought. If you haven’t already had a look, I highly recommend the following informative link: https://www.amsoil.com/lit/g2156.pdf
 
#19 ·
I run 20W/50 dinosaur oil ... no synthetic in my 40 year old motorcycle. Sometimes, I manage to spend the money for the 4T style, but often just run Castrol GTX. Every other oil change, I add ZDDP to replace what they removed from the oil a couple years ago. (The product I use is REALLY ZDDP and is called ZDDPlus)
 
#21 ·
What Oil

Thanks DAGAD. I always used GTX before and didn't have any problems although I am in the midst of a complete rebuild. GTX, however, has a SM rating which means that the phosporus and zinx wear additives needed in our bikes have been reduced to avoid damaging catalytic converters and to help meet pollution emission standards. SM rated oil also has a greater propensity for shearing. I am wondering where T100RC is getting his ZDDPlus. The addition of a wear additive should add to the overall performance of an SM oil in our bikes although it is still not designed for the higher demands made on a lubricant by an air cooled engine.

Will I continue with GTX? If there was a good deal to be had on synthetic motorcycle oil I'd use it in a heartbeat. It'd even be worth it to do an oil analysis at the usual change time to see what happened to the oil. I did notice a sale on Castrol Syntec which is however again a SM rated oil and comes in a 5W/50 grade. I was told that using an oil that has a lower viscosity than the recommended low end of the multi-grade makes no difference as the 5W rating viscosity is only available at below freezing temperature. I would still have to add a wear additive. If you could go 5 to 6 thousand miles between oil change intervals, the added cost of the premium oils wouldn't be so bad.
 
#22 · (Edited)
Morris oils

On the topic of non-detergent/detergent oil (as if Synth/non-Synth wasn't difficult enough), has anyone used, contemplated or heard of Morris low-detergent oils for vintage hardware?

http://www.morrislubricants.co.uk

I think if you look under the "classic/steam" section they have single wts oils and lubricants.

I mean, honestly, can anyone dislike a lubricant company that offers a section for "hygiene and cleaning"? :D

I think there is a supplier in Richmond, VA
 
#26 ·
Back in the sixties, Morris oils was considered very downmarket. I note ontheir website, if you go to the 4 stroke road bike ( V twin OIl) when you download the specification they dont tell you how much, or how little Zinc is in their oil. It could be none, or a lot.
 
#27 ·
Morris oils have a good rep in the UK, l have used their straight mineral oils as the sludge trap works with no detergent oils. Having said that l also used Duckhams " classic" 20-50 with no problems. Dare not try synthetics. Unless l put in a filter and morgo gear oil pump.
 
#28 · (Edited)
synthetic oil and filters

Thanks t100rc. I had a look at the ZDDPlus link. Another very informative site. Looks like a very good product to boot. Might have to try it

I agree and earlier cautioned that you should not use synthetic oil if you do not have an oil filter. Contaminants and dirt are less readily absorbed by this oil and instead held in suspension until the filter picks them up. On the other hand, due to the general stability of synthetic oil's viscosity across the full heat range, an anemic oil pump is more likely to provide better oil flow than a less stable product that may gel as it breaks down.

On a related vane, oil filters made for synthetic oil, filter to a smaller micron level. The standard SAE J806 filtration test calls for the typical paper element filter to trap somewhere around 40% of the particulate matter at 10 microns, 60% at 20 microns, 93% at 30 microns, and 97% at 40 microns. More advanced tests measure efficiency and service life. Newer high-performance filters really are better and outperform in all tests. Instead of traditional paper filtration, they use a synthetic or mixed paper/synthetic medium that reportedly removes in one pass up to 98% of particulate matter down to, as little as, 8 to 10 microns. Many of these newer filters incorporate high-flow features thus reducing backpressure. There are even some products that claim the ability to filter down to 5 microns. A micron is one millionth of a meter and is short for micrometer. For those more grounded in imperial measurement, a micron is 39 millionths of an inch (.000039"). To get a better visual, a grain of salt is about 60 microns and the human eye can see particles to about 40 microns.
 
#29 ·
Here's my 2 cents worth on syn oils. I use Amsoils in all my vehicles short of my wife's Durango and more on why later.

For bikes I use it because on air cooled bikes, syn holds up better in the high heat conditions. I work on turbines and if you put fossil oil in a gas turbine it would coke to carbon in a matter of a few hours. Syns were developed first by Germany in WWII because they ran out of fossil crude supplies and later were pressed into service for jet engines which run at much higher temps than recip engines.

For seasonal cars I use it because of the low acidity risks. A car that sits 6 months in a garage waiting for the snow to melt is probably at great risk for acid attack. So syn oil is my solution to that concern.

Experience-wise, a friend who sold Brit bikes for 45 years and is damn fine mechanic just had a Triumph rebuild come back because it smoked. It was the first bike he'd ever rebuilt and put syn oil into the bike from the start at the owner's request. He said the rings never seated. He rebuilt the top end again for free and used fossil oil to break it in. My experience was with my wife's Durango. At 35K Dodge put a new short block in the vehicle because the mains were not properly machined. So from 35k vehicle miles until today with 140K+ miles, the engine has only used Amsoil and their oil filters with a 7500 mile oil change interval. The engine does not burn a drop of oil, but uses about a quart every 500 miles. No drips, no known leaks. Just consumes oil. So, the argument that you can extend intervals without concern is not validated in my personal case. Maybe if you run their bypass filtration system you are okay. But if not, then my guess is the relief valve in the filter starts to operate and lapping compound begins to circulate thru your engine. I've moved to Mobil 1 for the wife's car just because it is easier to buy at Walmart for the frequent topping up. I'm staying with the 7500 mile interval only because it is too late now. But I'll never do that again and may very well, switch to fossil oil for her next vehicle with normal oil change intervals.

Last experience was with a friend who is a mechanic for a fleet of heavy equipment and over the road haulers. He talked his owner into going with Amsoil on a sample of vehicles. They change all their oils based on oil analysis because of the huge expense associate with oil for a large fleet. The analysis for the Amsoil vehicles shows a reduction in metallic contaminants down to nil. This implied internal wear was reduced to nil. It was this experience that convinced me to go with Amsoil years ago. My experience did not mirror his test results, but my guess is the filtration on my Durango versus his industrial engines is quite different.
regards,
Rob
 
#30 ·
l am sure one or more of you guys must have the anwser but why did Triumph design the twin without a filter?. l am sure that cars have had them since the thirties. Can the reason be that the system could not handle a filter and its pressure loss. Were the oils not compatible to low pressure oil systems. Is the bikes oil pressure lower than a car or just different?. Help!.
 
#31 ·
In part, it defies logic as to why they didn't add filters. In part, a closed mindedness of... did quite well without them in the thirties so why do we need them now especially when things are going along so nicely? The Bonnie and TR6 were really an updated Speed Twin designed and put into production in the thirties. Even the British bikes with filters such AJS/Matchless had only a very rudimentary element made up of a wadding material between two meshes that, like the screen in the Triumph, helped collect nothing much smaller than loose nuts and bolts. It’s like the question: why didn't they see the Japanese invasion coming in the early seventies and respond with an overall improved product? Remember that the British at the time were saddled with unmanageable labor problems and a corporate ideology that struggled to make a profit rather than improvement and design. By '71 the parent company lost what was then really big money and everyone asked how as it possible. The government tried to step in and save the company with the Norton-Villiers-Triumph arrangement which only led to a nearly two year worker's sit in. It was all too late. Sound a bit familiar - like the N/A car industry today?

In Triumph's case, to install a reliable oil filtration system, they would have had to re-design the entire engine lubrication system over to a more modern pressure lubrication system together with a better oil pump which would have meant further design changes. But then why stop just there? A lot of other updates were left lagging or were ignored.

There are a couple of really good books out there that track the British motorcycle industry by brand and in totality - melancholic stuff.
 
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