Engine oil

Previously wrote:

what would be the recomended engine oil to use in my dominator 99 of 1960 vintage. I have a gallon of monograde sae 50 that came with bike but it does seem rather thick. Any comments gratefully received

Jim Dracup

Hi Jim,

this is a matter of personal choice. The recommended engine oil for the Dominator range was 40 grade for summer use and 30 for winter use, but many riders will now swear by multigrade oils. If you decide on a modern multigrade make sure that the sludge trap in the crankshaft flywheel is clear as any oil containing detergents could loosen debris in the trap which could then mix with the oil and circulate throughout the engine.

Rob Gittins.

Hi James.

It depends mostly on what state your engine is, and what type of oils it has already been run on.

If has a lot of mileage on it and has been used with old type low detergent oils then you must stick with that type. This is because the engine will be very sludged up with black carbon and oil deposits especially the crank sludge trap. If you use high detergent oils with an engine in this state you start to loosen upthe sediment to mix in with the oil and it could cause havoc, especially with the big end shells.

If the engine has been stripped down, thoroughly cleaned, you can use modern car oils, even synthetic oils, BUT you must change the oil as soon as it gets slightly dirty and that could meen as little as 500 miles, and possibly never over 2000 mileswhich is expensive if you do choose synthetic type.

The reason for the low mileage is that modern highly detergent oils wash away the dirt and carry themto a very efficient cartridge filter thus keeping the wear particles out of the oil. This is why,a good quality oil with the correct API rating bought from a DIY chain or supermarket at lowish cost BUT changed at no more than 1000 miles can be a sensible choice.

As you know, the Norton engine does NOT have a cartridge filter and the gauze filters in the oil tank are absolutely useless for retaining anything smaller than about 1mm.

You could take a chance on modern oils with an old engine, but I would change the oils at perhaps 50 miles, 100 miles etc working up to a point that the oil look clean and stick with the 1000 mile changesat most changes.

By the way, never worry about the low end grade of a multigrade, even an oil with aviscocity of0w at thebottom end will STILL be THICKER cold than any 50 grade oil at 100 degrees C!

So you can be assured that if 40 or 50 grade is correct at running temperatures, then very low W figures are deffinitely NOT TOO THIN when cold, they just give your oil pump and relief valve and easier time and move nearly as quickly when cold as they do when hot.

Also, as you are changing the oil at such low usage, then the viscocity improver breakdown of multigradesdoes not come in to it, so you have nothing to fear..

That's my ha'pennies worth anyway.

Les H

Previously wrote:

Hi James.

It depends mostly on what state your engine is, and what type of oils it has already been run on.

If has a lot of mileage on it and has been used with old type low detergent oils then you must stick with that type. This is because the engine will be very sludged up with black carbon and oil deposits especially the crank sludge trap. If you use high detergent oils with an engine in this state you start to loosen upthe sediment to mix in with the oil and it could cause havoc, especially with the big end shells.

If the engine has been stripped down, thoroughly cleaned, you can use modern car oils, even synthetic oils, BUT you must change the oil as soon as it gets slightly dirty and that could meen as little as 500 miles, and possibly never over 2000 mileswhich is expensive if you do choose synthetic type.

The reason for the low mileage is that modern highly detergent oils wash away the dirt and carry themto a very efficient cartridge filter thus keeping the wear particles out of the oil. This is why,a good quality oil with the correct API rating bought from a DIY chain or supermarket at lowish cost BUT changed at no more than 1000 miles can be a sensible choice.

As you know, the Norton engine does NOT have a cartridge filter and the gauze filters in the oil tank are absolutely useless for retaining anything smaller than about 1mm.

You could take a chance on modern oils with an old engine, but I would change the oils at perhaps 50 miles, 100 miles etc working up to a point that the oil look clean and stick with the 1000 mile changesat most changes.

By the way, never worry about the low end grade of a multigrade, even an oil with aviscocity of0w at thebottom end will STILL be THICKER cold than any 50 grade oil at 100 degrees C!

So you can be assured that if 40 or 50 grade is correct at running temperatures, then very low W figures are deffinitely NOT TOO THIN when cold, they just give your oil pump and relief valve and easier time and move nearly as quickly when cold as they do when hot.

Also, as you are changing the oil at such low usage, then the viscocity improver breakdown of multigradesdoes not come in to it, so you have nothing to fear..

That's my ha'pennies worth anyway.

Les H

CORRECTION: I should have written:

The reason for the low mileage is that modern highly detergent oilsARE DESIGNED TO wash away the dirt and carry themto a very efficient cartridge filter thus keeping the wear particles out of the oil. As you know, the Norton engine does NOT have a cartridge filter and the gauze filters in the oil tank are absolutely useless for retaining anything smaller than about 1mm, so the only way to remove the dirt from the oil is for it tobe changed very frequently and in doing so take and remove the dirt with it. This is why,a good quality oil with the correct API rating bought from a DIY chain or supermarket at lowish cost BUT changed at no more than 1000 miles can be a sensible choice.

Previously wrote:

what would be the recomended engine oil to use in my dominator 99 of 1960 vintage. I have a gallon of monograde sae 50 that came with bike but it does seem rather thick. Any comments gratefully received

Jim Dracup

hello jim I run my 650 Norton Manxman On Millers 20/50 For the last three years Now and every thing fine I just change my oil once a Year Price 17 pound a gallon Its Very Good oil As for the mesh fillter in the oil tank its alot finer that 1mm you can get real fine brass mesh and fit inside of the origanl one if you are good with the soldering iron And there a bass mesh in the sump nut too ? Your Anna J Dixon

Hi Anna.

Even if the mesh filter could trap 1/5mm particles (which I very much doubt), a cartridge type filter typically filters down around 20 microns.

1/5 mm is 1/5,000 metre

20 microns is 1/50,000 metre

That is10 times SMALLER.

So you can see the cartridge filter, consideredabsolutely essential when plain bearings are used, is the reason why car engines (full of plain bearings) can run up to 100K miles or much more nowadays.

It is the microscopic debris, from the bore mainly, that wears away plain bearings, gears and cogs can cope with the debris somewhat better as they are case hardened, but they will also benefit.

If you want long engine life especially from your big ends, then you should keep your oil as clean as possibly, Oil changes are all that is available with the Norton engine (as standard)

Les H