Oil again

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MalcW
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Re: Oil again

Post by MalcW »

This has been an interesting thread. Although the handbook says use SAE 50 for summer and SAE 30 for winter, I use SAE 20/50 classic oil in my twin, as recommended elsewhere in this forum, based on it having big end shells rather than roller bearings. So far it's done a couple of thousand miles like this with no obvious issues. Should I continue to do so?

As far as the gearbox is concerned, I am using an EP oil; that will be coming out asap and will be replaced with SAE 50. I Googled (other search engines are available) EP oils and bronze, and there is quite a bit about it.

Malc
MalcW
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Re: Oil again

Post by MalcW »

MalcW wrote:This has been an interesting thread. Although the handbook says use SAE 50 for summer and SAE 30 for winter, I use SAE 20/50 classic oil in my twin, as recommended elsewhere in this forum, based on it having big end shells rather than roller bearings. So far it's done a couple of thousand miles like this with no obvious issues. Should I continue to do so?

As far as the gearbox is concerned, I am using an EP oil; that will be coming out asap and will be replaced with SAE 50. I Googled (other search engines are available) EP oils and bronze, and there is quite a bit about it.

Malc
Hi all. No thoughts on the use of 20/50 in a twin, as opposed to SAE 50?

Thanks,

Malc
SPRIDDLER
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Re: Oil again

Post by SPRIDDLER »

MalcW wrote: Hi all. No thoughts on the use of 20/50 in a twin, as opposed to SAE 50?
Oh dear, Malc, how long have you got?
I've never run a twin but there are very many here who have always used 20/50 in their twin engines for tens of thousands of miles without any issues.
In short, the perceived wisdom is that multigrade oil suits the twins' shell big end bearings, whereas mono suits roller/ball bearings better (no shell bearings on singles) as I understand that monograde has a greater shear strength.
Nevertheless, Duckhams 20/50 was the 'go to' oil for Mini engines in which the gearbox (ball bearings) used the same oil as the engine's shell big end and main bearings.
Personally I would be happy to use 20/50 in a twin but I've no reason to change from mono in a single as I've always found it totally satisfactory.
Last edited by SPRIDDLER on Sat Aug 31, 2019 7:23 am, edited 2 times in total.
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Dave T_LAPSED
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Re: Oil again

Post by Dave T_LAPSED »

I read, in my distant yoof, that when the con rod reaches TDC it decelerates the rollers in the big end due to it's change of angle and it was at that point that the rollers could skip and break through the oil film! Therefore 50 was preferable to 20/50 because even with the viscosity additives in the multigrade it was at base a 20 grade's oil film.
I ran my C15 and subsequently my Ducati 350 on 50 grade oil. My riding "technique" was, point in the general direction I wanted, then full throttle 'til flat out or I had to slow down, bend, junction, police car etc. I never had mechanical problems in either motor so, roller big ends it's monograde for me.
Dave, feeling very old!
david pollard
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Re: Oil again

Post by david pollard »

for what its worth, my bikes 18s/ rudge500/royal enfield wd/co and vincent twin all run on rock oil 20/60 fully synthetic and have done for 10 years or more, oil change every couple of years, no water absorption when stood in the garage in winter, fluid enough for a easy kick start when cold, every bike is fitted with magnetic drain plugs and also a magnet hanging in the oil tanks, no evidence of wear at all! yes its not as the book says but hey! this is 2019, oils have moved on!!
56G80S
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Re: Oil again

Post by 56G80S »

Oh no!

Some oil better than no oil, keep it checked. However, I think it's swapping from one to another that's the biggest issue, particularly from straight SAE to multigrade, detergent oils unless everything has been cleaned out throroughly of all accumulated debris.

For amusement value, I swapped from Duckhams 20/50 multigrade to straight SAE after a major rebuild many years ago. Were I to run again on multigrade I think I would fit a proper filter after ensuring any debris areas were pristine.

Frequency of oil change probably has more effect than which type - just make a choice and don't skip changes.

Johnny B
BRobbo
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Re: Oil again

Post by BRobbo »

I was hoping that there would be more on here about chain case oil as one contributor had raised a question on it. I'm using 50 mono in my CSR c/c but experience quite severe drag until after some 10 to 20 miles when all comes good. On dismantling cold I find that the plates are sticking together and presumably what is happening is that when warm the oil is sliding more readily off the plates and releasing its grip. The manuals I have don't seem to specify a grade for chain case oil. Sorry to drop another pebble in this ever growing pond!
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ajscomboman
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Re: Oil again

Post by ajscomboman »

BRobbo wrote:I was hoping that there would be more on here about chain case oil as one contributor had raised a question on it. I'm using 50 mono in my CSR c/c but experience quite severe drag until after some 10 to 20 miles when all comes good. On dismantling cold I find that the plates are sticking together and presumably what is happening is that when warm the oil is sliding more readily off the plates and releasing its grip. The manuals I have don't seem to specify a grade for chain case oil. Sorry to drop another pebble in this ever growing pond!
Too heavy Barrie, max weight is SAE30 or 20, you can use ATF as that's approx 20 weight.
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Rob Harknett
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Re: Oil again

Post by Rob Harknett »

You may not be able to go by the book for chain case oil. The metallic parts it needs to lubricate may not be too fussy. Clutch plates may be fussy. However 9/10 times it is the bike owners that are too fussy, in their expectations of a now 70 year old bike + / - a few decades each way. They will have no idea, what they consider as something not acceptable, is actually more superior than when the bike was new. I can relate back to when my 55 G3LS was 9 months old. It had all the so called faults then, that are complained about now. Some when everything was considered perfect.
McMaz
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Re: Oil again

Post by McMaz »

I recently entered this oil-choice minefield when I needed to purchase engine oil for my 350. After reading lots of conflicting advice and information I thought it best to do some research myself. Here's what I came up with but acknowledge it's down to each owner to decide what's best.

Multigrade or monograde?
Monograde oils are shear stable therefore are a good choice for engines with big end roller bearings which create a cavitation zone in the oil which causes high shear conditions. They provide a consistent film strength but their downside is that they are not good for cold weather start up. In the UK it would appear sensible to use an SAE 30 from November to April and SAE 50 from May to October for best protection of the engine.

Multigrades perform a great service by not being too thick at cold startup to prevent engine wear by providing more instantaneous oil flow to critical engine parts and therefore can be used all year round. However, they are prone to shear to the extent that the oil may no long resist thinning; viscosity loss in an engine is regarded to be more harmful than an increase in viscosity. The 1959 Matchless instruction manual, which covers both single and twin models, states “The use of multigrade oils is not recommended”.

Detergent
Even in a thoroughly cleaned engine, only use a none or low detergent type oil made for ‘classic' engines unless an after-market cartridge type oil filter is fitted. This is because higher detergent oils are designed to keep contaminants in suspension and a mesh gauze filter is not efficient enough to remove this suspended material. None or low detergent oils allow contaminants to settle in the sump and not be recirculated in the oil.


So I decided that the low detergent monogrades were the best choice for my bike. I then emailed the oil manufacturer with the 350's details to confirm that they considered that it was the correct choice. They replied saying, if the engine is completely standard, they would recommend the use of a monograde to stay with the motorcycle's original oil recommendations. However, they also recommended the use of SAE 40 as an all year around grade, which is something that I had not considered or seen elsewhere.

As I said at the start, the choice of oil is down to the best judgement of the individual. I think Johnny B (Tue Sep 03, 2019 1:37 pm) gives wise advice – “Some oil better than no oil, keep it checked… don't skip changes”.

Sean
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