Oils

[AngleseyAJS]

Good afternoon everyone,

I have an 1955 AJS 18s and I'm in the process of going through it and sorting out the problems it had when i bought it, which is thankfully nearly finished!

I'm planning on changing the oils etc, looking in the archive it says either SAE50 for summer riding or SAE30 for winter and the same for the gearbox and i assume for the chain case?

While I'm not planning on winter riding as such but if it was rideable this weekend then i would definitely be out on it, as soon as they grit the roads that's my sign to wrap it up for winter!
Is it worth using SAE30 at the moment or will SAE50 be okay?

I've had a look locally and nobody stocks SAE50, My question then is there a modern version of it or do i go for a multi grade ?
Should i go with semi or stick to traditional mineral?
Which brand do you prefer?
Which would you NOT use?

How many miles do you do before an oil change?
I know whats recommended but our bikes are much older now than when the recommendations were first suggested.

SAE20 is the recommended Fork oil in the instruction manual, has that been upgraded over the year?

On a side note what are your thoughts on spark plugs?
Which make and model do you prefer?

Many thanks in advance
Chris

[dave16mct]

SAE50 will be OK. You can get any classic oils from here: https://www.opieoils.co.uk/c-1489-class ... -oils.aspx
I use Champion N5C plugs and SAE20 in the forks. I change the engine oil once a year.
Dave.

[SPRIDDLER]

This question occurs quite frequently and there are many opinions.
However, for more than 20 years I've used Morris Oils SAE50 in the engine and gearbox all year and 30 in the chaincase all year for my '54 G3LS single, changing the engine oil about every 1500 miles. Champion N5C sparkling plug.
It's said that if you use multigrade in an engine that hasn't been stripped and thoroughly cleaned then sludge can be dislodged in the engine and the oil tank by the detergent additives in multigrade. I've never used multigrade so can't offer an opinion.
Do not use multigrade in the chaincase as it contains anti-friction additives which isn't what you want on the clutch plates.
SAE 20 for the fork dampers. Anything heavier will stiffen the action and the opposite if thinner is used.
Twins can benefit from multigrade on account of having shell big end and main bearings that rely on fairly high oil pressure to maintain a lubricating film but the singles have ball/roller main and big end bearings which only need (and receive) a weak oil feed in pulses from the reciprocating pump and splash, rather than from the higher and constant pressure from the rotary pump(s) of the twins.

The oil pump in singles..........

Oil pump action..gif

[AngleseyAJS]

SAE50 will be OK. You can get any classic oils from here: https://www.opieoils.co.uk/c-1489-class ... -oils.aspx
I use Champion N5C plugs and SAE20 in the forks. I change the engine oil once a year.
Dave.

I'll have a look at that site,
Thanks very much Dave, much appreciated

[AngleseyAJS]

This question occurs quite frequently and there are many opinions.
However, for more than 20 years I've used Morris Oils SAE50 in the engine and gearbox all year and 30 in the chaincase all year for my '54 G3LS single, changing the engine oil about every 1500 miles. Champion N5C sparkling plug.
It's said that if you use multigrade in an engine that hasn't been stripped and thoroughly cleaned then sludge can be dislodged in the engine and the oil tank by the detergent additives in multigrade. I've never used multigrade so can't offer an opinion.
Do not use multigrade in the chaincase as it contains anti-friction additives which isn't what you want on the clutch plates.
SAE 20 for the fork dampers. Anything heavier will stiffen the action and the opposite if thinner is used.
Twins can benefit from multigrade on account of having shell big end and main bearings that rely on fairly high oil pressure to maintain a lubricating film but the singles have ball/roller main and big end bearings which only need (and receive) a weak oil feed in pulses from the reciprocating pump and splash, rather than from the higher and constant pressure from the rotary pump(s) of the twins.

The oil pump in singles..........

Oil pump action..gif

Thank you for the info, i was looking at Morris oils so that's a good vote for them.
There's not a stockiest locally so I'll order from them online.

Can i make do with 50 in the chain case or is 30 better?

I'll definitely go with the Champion.

Interesting about the twins, I did look at a 31 CSR but the bike just wasn't original so went with the big single instead.

Thanks again
Chris

[SPRIDDLER]

No. I wouldn't as it can cause the clutch to drag. Some have used automatic transmission oil (ATF) in the chaincase but I've no knowledge of whether it's satisfactory or not.

TIP.
If you're not using one, club spares have an improved rubber sealing band for the chaincase.

[AngleseyAJS]

No. I wouldn't as it can cause the clutch to drag. Some have used automatic transmission oil (ATF) in the chaincase but I've no knowledge of whether it's satisfactory or not.

TIP.
If you're not using one, club spares have an improved rubber sealing band for the chaincase.

Thanks for the advice, I'll definitely go for the 30 then as its sounds like it will be less problematic in the long run.

As for the chaincase sealing band, got one on my last order! I had seen a few people mention them so went with it.
I've got to pluck up the courage to seal the exhaust with silicone sealant next!!

[SPRIDDLER]

Deleted. Duplication of post below.

[SPRIDDLER]

I've got to pluck up the courage to seal the exhaust with silicone sealant next!!

I find it an awkward job manoeuvring the sealant gun/tube around the back and under the pipe (with a shaky hand) so to achieve a clean result I put masking tape around the pipe then when the sealant has set I remove the tape after running a sharp knife around it close to the head.

[Mollbhan]

Screwfix has a (no nonsense oil) which I am told is grade 30 with no additives, perfect for the chaincase, I use it in the engine too and have never had any problems. Being fairly cheap oil changes are not expensive. I always leave the engine on compression and find I can leave it for several weeks with no wet sumping taking place, I know this subject has been debated before and maybe I have just been lucky but it works for me.