Hello,
Could anybody suggest better oil for temperatures below -5 for M20. I have mix of sae 50 and sae 30 monograde in oil tank. I did 35km today. After ride drained both tank and engine. Seems too thick to me even when hot. Can I use 20w50 in winter?

Kalle

email (option): kalle.tikas@gmail.com

Why not run on straight 30. Years ago when I had my old 1952 Panther it was recommended to use 50 in the summer and 30 in the winter.

After talking about oil viscosity with my granddad and uncle who all worked at the Bsa and manny other old timer's they all said that the thickness of straight 50 today was the same as straight 30 of the 1930's and 40's and oss oil refiners near to were i live have also verified this. I run a 1938 Bsa M22 sports racer and my Bsa Wm20 and my 1934 Bsa saloon car on straight 50 and have done so for the past three years and i have had no problems at all . I never change to a 30 or a 40 in winter times , I just start the motor gentle warm them before starting any journey. the oil will thin itself as the Engine gets warmer i generally do and oil change once a year what ever the milage is and its normally about 3000 in the car and about 1500 to 2000 on the bikes . I also put straight 50 in a 1923 Bsa 11 hp car the only one known left in the world and a pal of mine puts it into his 1923 Daimler both cars worth over £20000 and they are still running strong ..... But i must say iv never run them at -5 ! how new is your engine i.e. has it been recently rebuilt and cleaned through out ??
if so a friend of mine runs his on 20/50 as its a lot cheaper around my part of the world and he's done so for about five years with no problems either , but remember try not to mix oils as they can congeal and block oil pumps ect

but i would say its up to the individual , put in what you feel comfortable with
hope this helps Gary

email (option): garypitt@talktalk.net

For what it's worth my opinion is that if you have older machines then 20/50 or 10/40 which is more common these days is fine, the only thing to be concerned about is regular changes regardless of "original" recommendations.
Filteration has a lot to do with it; modern cars are very good and probably are bikes, I wouldn't know. So for my machinery,the Rickman cars (look it up) with Ford engines it's 3000 miles and a filter, for the bigger bikes it's 2000 and a filter if they have got one and for the little bikes it's 1000 + filter.
On older bikes, M20 and G3L the filter is fairly useless in modern terms so the only option is regular changes. This of course means that you get through a fair amount of oil if you put the mileage in but against that if you shop wisely it is still more affordable than it was some years ago. Try ASDA for GTX at £13 for 4 liters when on offer or buy 25 liters from a wholesaler like New Era Oils.
However I have a big bother who fundamentally disagrees with me on this and we have spent many evenings in the pub arguing the toss! Hay Ho...

Catastrophic engine failure or premature wear are the likely indicators of a badly out of spec. oil I would have thought...

I've used all sorts of oil from Morris's and Silkolene monogrades through 'common' multigrades such as GTX and Duckhams to unheard of generic supermarket brands...

I've never had a catastrophic engine failure I could put down to a lubrication problem...I may have worn some engines out prematurely but how do you know?....Any expectation of how long an engine will last is only theoretical and there are other factors involved as well..

In the real world these days not many riders do enough miles to wear out the engines of their 'classic' bikes...Most of my friends do between 0 and 2,000 miles a year....

At that rate it's going to be at least 25 years before they encounter oil related wear problems I would have thought....

At temperatures of -5 I would go with an SAE 30 or a 20/50 multigrade and give the old girl some time to warm up after starting..That always worked for me riding to work every day in the winter.....Ian

email (option): ian@wright52.plus.com

My last "classic" daily driver was a WD M20 which I used for about 7 years or so, 5-6,000 miles per year. No major work of any kind and no failure whatsoever (except a spark-plug problem which drove me nuts before I realized what was happenning). Modern 20W-50 throughout the year. When I put it away in favor of a more modern ride, it was still a one- or two-kick starter.

email (option): jonny.rudge@verizon.net

Thanks.
My engine is done about 4500 miles from rebuild and I used sae50 in summertime. Problem is that oil doesn't warm up enough in separate oil tank at -5C. During 1 hour riding. I already drained oil and will fill tank with fresh sae30 for winter (r)fun.



Kalle

email (option): kalle.tikas@gmail.com

Ian has got it in one.
more important than what goes in the tank is how long it is in there for.
99.99999999999999999999999999999999999999999999999999999999999 %
of everything you will read on the net about oil is totally irrelevant to the dinosaurs we are riding.
FWIW I ran 20w 50 in my M20 for 13 years with no ill effects.
I used the multigrade in the bike because I used the same oil in the work vans and eventually the hire cars.
It just got silly keeping 1/2 dozen different oil.
I now run 30wt lawnmower oil in the M20 because I get it wholesale so it is very very cheap.
Also no obvious ill effects.
If your oil is not getting too hot to touch the oiltank then I would consider going to lighter oil.
Honda recommend 10w30 at -10 deg in their air cooled mower engines and stationary motors so a similar viscosity should not be a problem in your M20, particularly if you changed it regularly.

email (option): wariron@tpg,com,au

The oil in the tank should only get warm not too hot to touch!!

Operating temperature for most auto oils is 100 deg C
Minimum temperature should be 80 deg C
Water temperature should be between 80 & 120 deg C

That is what the second number on multigrade oil is.
20w40 ;- 20wt= viscosity at 20 deg C : 40 = the viscosity at 100 deg C.
A little trap here is the higher reading means the SAME viscosity as 40 W at 100 deg C not the same viscosity as 40wt at 20 deg C.
Multigrades do not get thicker as they get hotter they get thinner more slowly than the same monograde oil.

Or to put it more clearly.
5W40 , 10W40, 20W40 and strait 40 will all be exactly the same viscosity at 100 deg C

But at room ( normal room any way ) temperature of 20 deg C the strait 40 will have a much higher viscosity than all the others.

The only real down side of multigrade oils is at room temperature they are much thinner than monogrades so will tend to wet sump much more easily so just watch out for a sump full of oil & an empty oil tank.

email (option): wariron@tpg,com,au

Yes but thats 100 deg C inside the engine. I repeat the oil tank will only get warm on a long run NOT hot enough to boil water!!!

That's the reason that both Velocette and Matchless/AJS put heart shields on their oil tanks?