I have a 1955 BSA 650cc Road Rocket. What I have been using #30 weight non-detergent oil in the crankcase. I talk to another shop that it should be #20-50 synthetic.I did put it in briefly and it seems to smoke blue so I put it back to non-detergent. Does that make any sense?..
I wouldn't recommend synthetic oil in an A10. A year or two ago I changed from SAE40 to 20-50 with no problems. What I did notice was that the new oil became dirty very quickly and needed a change after a few hundred miles. Presumably the higher detergent content was lifting deposits that were lurking in the engine.
The esters in synthetic have a reputation for shrinking oil seals which can lead to leaks appearing.
wouldnt use synthetic , it wasnt about in the day. used for higher revving modern motors with different compund rubber and gaskets smaller oil ways.
dont like modern 'superbike' oils in classics due to detergent removing whats needed from soft metal bushes, modern engines are roller or ball bearings, classics have phosphor bronze or bi metal surfaces.
Im old fasioned, still use Castrol straight 40 'Wakefield' oil , 20-50 probably ok but as we dont ride in cold temperatures is it needed? 10-40 too thin.
If I use what the book says the customer cant complain
I use Morris 20/50 in my A10 which is used all through the year.
It gets changed regularly.
i m using fully synthetic oil in my a10 engine only without major issues. it will sludge up in winter though and the easy return can become the breather, so drips onto the clean patio. i think bsa were right when they recommended straight oil and oil changes for the seasons but its not always easy to buy.
You have to remember that back in BSA's hey days only straight oils were readily available so it was grade 30 for winter and grade 50 for summer. After the introduction of multigrades then most people moved to 20/50 multigrade. I myself have been using Halfords 20/50 multigrade Classic Oil for quite a number of years now on at least 4 different bikes and am at present using it on my A7 and A65, Julian is correct in saying that the main thing to do is to change the oil on a regular basis and also the filter if you have an inline filter. These BSA,s are not like modern high reving super bikes that need specialist oils.
The Tech answer is that Straight Grades allow the crud to sink to the bottom of the crankcase or sump if you have one and stay there. The Multigrades are design to hold the crud in suspension so it gets strained out in the cartridge oil filter.
So, a straight grade is good if you don't have a cartridge oil filter and rely on cleaning out the bottom 'sump' and gauze on a regular basis but a multigrade is better if you have a filter.
There is a school of thought that Multigrade also cleans the engine as it goes due to it containing detergents, but the straight grades these days probably also has these aswell. The concern by many is that if you put multi-grade in an engine that has been run on straight grade it will clean the muck off and that could get into the bearings etc. My view on this is , so what?? The muck is generally carbon and is unlikely to come off in big lumps so I cant see it doing any significant damage! In fact, better to let the Multigrade clean it off gradually and leave behind in the filter surely.
The main thing is to change the oil every 1000 miles or a bit longer if, due to leaks/burning etc. you're utting a pint in every 200 miles anyway.
Regarding the use of synthetics, only my opinion but I wouldn't. Firstly, they are developed for engines made with close tolerances, secondly, they are very expensive compared to mineral oil and thirdly when they leak or drip on to hot surfaces, they stink like melting plastic, a horrible smell. However, if you feel that's the oil for you, I never heard of any hard evidence that it will damage our old clunkers, so its up to you.
Just my opinions.
Chris
Chaz
only recently got my A10, like the sound of the castrol straight 40, where is the best place to get it.
what do you recommend for the chaincase.
Morris oils are good and freely available mail order. I use their Straight 40 in the B31 and their 20-50 in the A7 and A10. I use tractor universal 10-30 in the primary chaincases and forks. And the tractors. It's a both diesel engine oil and hydraulic oil and it's used for oil-immersed brakes (a good thing in tractors, not so good on BSAs). It's also cheap...
my local supplier has Castrol straight oils, Rob Hunter in the western area supplies trade so anyone they supply can get.
you could try
https://www.classicoils.co.uk/
https://www.opieoils.co.uk/c-2150-castrol-classic.aspx
as a motorcycle repair/service person I stick with what I know, if tractor oils caused a problem to a customers bike who has to pay the repair?
being near Swindon, we can get help from their helpdesk.
the story went, that Castrol stopped straight grade oils , then (I think) the MG Owners club asked for a batch run of straight grade, Castrol Wakefield said no demand unless they could find enough for a batch to be created. After asking various owners clubs there was a demand which has now become a range again. HAd it not been requested we would not have the choice now and subsequently Morris, Silkolene, Millers etc would not be producing now.
thanks for the replies, going to go castrol
Hi all,
Yes the non-detergent oil is meant to allow the crud to drop down to the bottom of the tank and sump but it also allows the accumulation of stuff in the sludge trap in the crank. This was a design feature making use of centrifugal force, hence the need to strip an engine quite frequently to clean out the sludge trap. How many engines have come to a premature end through rebuilds not including the cleaning of the sludge traps? Also, high mileage bikes when stripped are found to have, due to the build up of sludge, barely enough oil reaching the lefthand big end to prevent a seizure
When using a full detergent 20/50 the in-line filter is essential to take the sludge out of circulation. Oil changes can be at the BSA recommended intervals and so can a new filter although it would probably be good for a few oil changes why risk it.
Having inspected a crank after about 70,000+ miles I can confirm the lack of sludge in the crank and the still perfect fit of the big end shells.
I would be a bit cautious if starting to use a full detergent oil in and engine run on non-detergent oil for anything but a short time. The detergents will mobilise some of the deposits to perhaps cause problems elsewhere.
Dave.
I would go along with much of what has been said, but........I would add that you put a detergent oil in a dirty (internally) engine at your peril. Doing just that nearly cost my pal a lot of money. The dirt clogged the return side of his A10 very badly and the engine had to be fully stripped and thoroughly cleaned. If you have rebuilt an A10 engine including the crankshaft sludge trap and you can eat your dinner out off it, by all means use a detergent oil. If it cannot be described as immaculate inside, then I would use an in line filter too.