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Extending Service Intervals

Extending Service Intervals

Extending Service Intervals

I am interested in extending the fluid change intervals for an old design of motorcyle. It was designed with late 1930's technology and has very frequent fluid changes recommended.

Currently the specifications are -
Engine - SAE20W/50 2.3L change interval 2500Km
Transmission - SAE 20W/50 1.1L change interval 10000Km
Final Drive - 90EP 110 ML change interval 10000Km

I am aware that a change to synthetics may allow us to extend change intervals, but wonder what the downsides are?

RE: Extending Service Intervals

You give a viscosity spec. for the engine oil, but not a performance spec (API SA, SF, SG, etc.).  While later performance specs can run much longer than earlier, a loose engine will dump more blow-by into the crankcase than a newer tighter one shortening the oil's life.  So if they specify SA, SB, or whatever you could extend with confidence, but if they specify SF you might hesitate.

You say it's an old design instead of an antique, and if you're spinning up enough miles to raise the issue it must be a daily driver.  Are we talking about a Ural here?  Putting western synthetics into a bike designed to run on Soviet Swill(TM) lubricants would be ridiculously excessive, IMO ;).  Give it generic lubricants and it will last much longer than you'll want it to.

RE: Extending Service Intervals

Yes , it is a Ural and it is a daily driver. It is a 1970 M63 solo, but with a later (mid '80's) 8.123 engine (they have an oilfilter). I rebuilt the top-end last year with new pistons and rings, which raised the compression ratio to 8.8:1 and had new seats and valves fitted so it would run on ULP. But at between 800-1000 klm a week, the service intervals are far to short.

Additionally, advice from other owners and even various importers is all very contradictory. There is a great deal of confusion resulting from the differences between the varying Ural engines, Dnepr engines and BMW /2 engines. Same with the gearboxes.

For example, I have been variously advised to use engine oil, ATF or 75/90 gearbox oil. At least with the final drive the recommendations were to stick with the standard 90EP or go to a newer 90/120.

If I can find a solution that will safely allow interval extensions to say 5000 km for the engine and 15000 for the transmission and final drive, then I'll be happy. A solution that will turn it into a quarterly event will have me over the moon!

RE: Extending Service Intervals

The majority of old bike engines were built for heavy single viscosity oil like SAE 50. This allowed loose tolerances without excess blowby or leaks.
The synthetics are generally thinner in terms of what you would see and "pouring viscosity" but make up the 50w rating with film strength modifiers. I'd guess a 20w50 synthetic may not stay with the engine for your desired change interval.
Remember that the Ural is a knockoff of the BMW and they likely copied the recomendations from that manual with little R&D.
Change interval is determined by oil quality, engine condition (blowby, etc) and driving style. IF you're just making short trips on a daily basis, you would be better to stay with the current change time. Long touring runs where the engine stays hot and burns off the fuel and water in the oil can easily go double the mileage with a good brand of oil.
The only real way to determine what you need to do is by oil analysis that compares your used oil to a sample of new oil. This will tell you the condition of the lube under your driving conditions. Its about $35 USD here.

Keep the wheels on the ground

RE: Extending Service Intervals

I'd like to modify slightly what Sprintcar has to say about synthetics.  Not all synthetics are the same and maybe that he is referring to is a light base stock with VI added. One that does not and will not shear back (or loose viscocity on hard use) is Amsoil 20W-50 Motorcycle oil or their old standard 20W-50 Racing Oil because it has no VI.  The old wives tale that synthetics are thinner comes from the uneducated in that viscocity rating is not based on what you see when you pour it out of the bottle, it's at 100 degC (or 212 degF) and at that temp if it is "in grade" it meets SAE grade for viscocity.  Synthetics just don't get as thick at room temps and hence people want to say they are thinner.
Sprintcar is right that the only way is to have a sample taken an analyzed.  Amsoil will provide a detailed spectrographic analysis for about $15 or $16.
My experience is that I have been using them since 1978 and as an engineer have taken a keen interest into them, first for my own equipment (I turbocharged a BMW car in 1978 before all those turbos were around and wanted a better oil).  I can safely say based on analysis results that the service life will be 4+ times whatever the mfr's recommendations are.  I was impressed an became a dealer.

RE: Extending Service Intervals

I can't see what the advantage of extending oil service intervals to automotive standards in a motorcycle is.  The things that can happen on a bike when systems fail demand a bit more frequent attention, IMO.  A couple thousand miles on a vintage bike is enough for me.  I service my 1948 Norton with Castrol 20W-50 engine oil and ATF in the gearbox and primary case (I know, I know---y'all don't like the idea, but it has worked for me for many years).
Even when I rode everyday on my last Goldwing I changed oil and filter every two to three thousand miles.  Keep in mind that rear tires only last ~10,000 miles!


RE: Extending Service Intervals

Thanks very much for the replies, they and some in the Synthetics threads have been quite interesting. To answer evelrod, the desire to extend service intervals is a lifestyle thing. I enjoy playing happy family on the weekend and if I can have more time with my kids then great. I fully understand the importance of system checks on a bike and carry out daily pre-ride checks. However if I can extend the engine oil change interval to 5000 or even 7500 km and the transmission and final drive interval to 15000 (which correlates to rear tyre replacement) then I'll be very happy. That will mean one Saturday devoted to servicing every 3-4 months. I am quite interested in why you use ATF in your gearbox. That or 75/90 gearbox oil is used by many UK Ural riders. I can understand with wet clutches why ATF is used, but why in a seperate gearbox?

RE: Extending Service Intervals

It was common practice in British bikes (cars, too, before the "Americanization" of the industry in the UK) to use the same type lubrication in both engine and gearbox.  My Norton specs are for a "50" in both.  I use Castrol 20W-50 in the engine (convenience, cost, availibility, personal preferance, experience, whatever!) but I switched to ATF in the gearbox to smooth out the rather 'notchy' gearchanges.  It's an old design gearbox dating to the 30's but, it seems to thrive on the lighter oil.  I have used ATF in all my  racing gearboxes (Ford/Lotus UK and Jack Knight) and in my street cars using the BW T-5 (OEM spec) with absolutely no difficulties since I started this practice in 1967. I have said in these forums many times that I adhere to this practice on my own and do not recommend that it be used by all.  Just giving you an insight to my experience.  It works for me!  However, I still use gearoil in the box of my old Ford Model A (SAE 90 as opposed to the OEM "600W"). Same deal for my 1937 Buick but "engine oil" in the 1959 Nash Metropolitan (Similar specs as MGA 1500).  My Austin Cooper uses the same lubricant, engine/gearbox, by design and I use Mobil 1 15W-50, TWO magnets in the oil pickup with a 19 row Mocal oil cooler and a remotely mounted Wix 51515R filter all hooked up with AN -10 lines.
Back to the "time"---bike question---It only takes me about 10 minutes to service the Norton (it is a dry sump) but even my Goldwing could be completely serviced in about a half hour! I spend more time lubing my chain and wipeilng down the "oil" (it IS British, afterall!)
You just need more "face to face" with these old bikes and cars.  My wifes Lincoln gets serviced by the dealer every few months and other than that, all it ever gets is the occasional wash and, of course, fuel!!!
I live by the old cliche---"Nothing ventured, nothing gained"  

Best of luck and "Believe only half of what you see and none of what you hear!"


RE: Extending Service Intervals

Extending service life oil is an environmental improvement all around from source to disposal.

RE: Extending Service Intervals

Aside from the time/expense, which isn't that big a deal- it can really be a pain when the service interval comes up at the same time you have 2-3 weekends tied up in a row!
The other nuisance, is when you are travelling a distance. For a 1000 mile oil change interval (back when I had my '70 Honda CB750) I would have to change the oil halfway into the interval before going on vacation, or change it on the road.
I went to synthetic, and ran it about 6000 miles between changes. I switched at about 60,000 miles (not km) and ran it that way to ? 90,000 plus miles.
Sure was nice to have that extended interval.


Jay Maechtlen

RE: Extending Service Intervals

I agree with the majority vote here!

As I understand it there are 2 main reasons for having to change the engine oil.

1. Oil gets thinner and less effective as it gets old. Modern synthetics aren't as anywhere near as prone to this as the older spec mineral oils were......

2. Oil gets contaminated by products of combustion, including abrasive particulates. An engine without a filter needs very regular oil changes or these are continuously going round the bearings. You have now changed to a filtered system.....

Your old transmission hasn't changed but again, modern oils have improved way beyond the capabilities of only a few years ago. Does the old transmission oil appear to be contaminated (change colour or contain metal particles)? If not, there would seem to be little reason to keep changing it. Many modern cars don't even have a drain plug in the diff.....

Get my drift? I would personally try modern higher spec. oils, monitor the situation and spend more time with the kids.

RE: Extending Service Intervals

gregservice, if you want to do extended oil changes, you need a quality oil and the second best oil I have found is from http://www.texasrefinery.com/ ....I haven`t found the best yet. People promote Amsoil, but from what I have seen in engines ran several thousand miles on it, it just doesn`t cut the mustard. (You wouldn`t believe the build up of crud inside engines ran on it.) TRC is to Amsoil as Amsoil is to your $1.39/L grocery store discount oil. PLUS, with TRC you get free engine oil analasys.... and no, I have no interests in the company, I just like to see people able to buy quality. We, the consumer, have been paying premium prices  for second rate merchandise and shoddy workmanship for so long we think it`s normal.

RE: Extending Service Intervals

To carbulcle,
You must have seen a very limited circumstance.  But if you surveyed say 10 or more installations of the use of Amsoil, the data shows otherwise, along with 3rd party oil analysis results.

RE: Extending Service Intervals

I have used Amsoil, Mobil 1, A full synthetic marketed by Nissan, Castrol Synthetic R and others. They all worked fine.

Amsoil make a fine product, my only gripe is their dodgy marketing practices. Looks like a Pyramid structure to me.


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RE: Extending Service Intervals

to patprimmer:
You are mixing marketing methodology with this thechnical forum.
Do you know what a pirmad scheme is?  If you were in busines, you could obtain a business account just like with any other company.  A small company with limited cash for advertising uses different methods to get the product out.
Anyway, glad to hear you are not stoning the quality of the product. Simply using the product "with no problems" isn't good enough for comparison purposes.  I use them based on their technical qualities and have since 1978.  Just one of the qualities is volatility and is lower than any of the other brands you mention.  Low volatility keeps lube on hot surfaces.  Upper cylinder areas will not see the taper wear and ring grooves will remain free of the normal heavy varnish.  I have automotive engines with honing marks in the cylinder walls at over 80k miles to demonstrate the point.
Also, most American made oils cannot meet the European volatility requirements for high speed use.
Besides, no other brand will warrantee their product to go the distance.

RE: Extending Service Intervals


I just call it as I see it.

If you are going to dispute what I say, at least get your quote right. I never said I simply used it with no problems. I have infact used amsoil, Mobil 1 and the lightweight Nissan oil to overcome specific problems or to give a specific advantage at the time. They all solved the specific problem that I chose them for. I don't really feel I need to explain my test methods nor specific requirements to justify a comment that they all worked fine.

As you say, this is an engineering forum, not a commercial free for all, that is why I recomend more than one brand wherever possible. From my observations on this forum, the most frequent problems involving plugging one product have been traced to Amsoil salesmen, resulting in a number of red flags for commercial abuse of the forum.

Yes I do know what a pyramid is, and I have previously bought Amsoil from various levels of the pyramid. I was also offered a deal to be part of it.

As I from time to time, have applications that require a number of the properties of Amsoil, I do like to buy it from time to time. I would much prefer to buy it from an official regional distributor, or from a convenctional retail outlet.

These are my personal views, and do not necessarily reflect the views of the management of this forum.


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