What Oils?

Information relating to the Matchless G12 or AJS Model 31 650cc twin
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Chessiegolf
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What Oils?

Post by Chessiegolf »

I've recently read an article in Classic Bike Guide about the advancement in oils since the time our bikes were manufactured. The article advised that virtually any oil today is better than in the 1950s and 60s and there was little advantage in using single grade oil.

What is the consensus on the type (not asking for manufacturer) of oil that should be used in the engine, the gearbox and the primary chaincase?
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Eamonn
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Re: What Oils?

Post by Eamonn »

Using the "Search" button (looks like a small magnifying glass) at the top of the page, you can list all the entries on oil within the Forum and have many happy hours researching the information provided.

It is a very commonly asked question, and there are many different viewpoints - so it is important you consider the various opinions and make your decision.

:D
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Chessiegolf
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Re: What Oils?

Post by Chessiegolf »

Ok Eamonn, thanks for that. I'll do a search
Stan Palmer
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Re: What Oils?

Post by Stan Palmer »

There is some conflicting information about, for instance one manufacturer made the case for correct replacement of straight 50 being not 20/50 multigrade but something like 30/80 (can't remember the exact figures). It was to do with how viscosity is measured at temperature.
For that reason I went back to straight 50 on the 350, it did reduce a slight piston slap I had once warm.
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Chessiegolf
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Re: What Oils?

Post by Chessiegolf »

Stan,
What oil do you put in the gearbox and primary chaincase?
Also the original manual says to change the engine oil in an infrequently used machine every 3 months, irrespective of miles covered, does that philosophy hold true for modern oils?
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Re: What Oils?

Post by Stan Palmer »

I used straight 50 for the chaincase and a high quality modern four stroke gearbox oil. That was to cure a whine in 3rd gear.
I am far from an expert on using these bikes, my hobby was building them. I didn't use any of then much.
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Re: What Oils?

Post by 56G80S »

I personally "blend" the engine oil (SAE50) with automatic transmission fluid (ATF) for the primary chaincase.

I use the engine oil straight into the gearbox. You'll see on a search that there was once quite a discussion about not using modern EP gearbox oil for fear of damage to bushings.

Pays your money and takes your choice but even back in the 1970's when I was using Duckhams 20/50 that worked fine. The AMC box that was in then is just out as part of other work and although working OK I will be fitting another box in so I can check and replace any worn parts in the current box.

Johnny B
Chessiegolf
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Re: What Oils?

Post by Chessiegolf »

Thanks for the help. I've just changed the gearbox oil from SAE 40 to EP 80, I'd better drain it out again.
The gear change seems slow to me, so wondered if a change of oil would help - I've ridden 60 miles today on the EP80 and I can't discern a difference, but if there's a chance that the bushes could be damaged by gear oil, then I'll go back to engine oil.
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les ward
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Re: What Oils?

Post by les ward »

I have used EP90 in all my gearboxes for years. When I replaced the layshaft bearing on my Commando the bushes were well within tolerence and they have been in EP90 for 30+ years. So I wouldn't worry, if it was me.
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Re: What Oils?

Post by 56G80S »

I didn't say do it, I was referring to a discussion about it.

Corporal Jones job here. (Dad's Army)

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