What oil should I use in a Model 50

I fitted a Hi de Hi oil filter kit to both my ES2's. They use a paper element from a T*****h Trident. Use any good quality classic 20/50, Halfords is not too bad. Straight 50 or 30 is old technology and a good multigrade is better in that it has detergents and anti condensation properties as well as loads of other helpful bits. API 20/50 followed by the letters UP TO sj only. SJ and higher are for liquid cooled engines only.

However, if you use any old oil, or a top quallity jobbie. just change it regularly and make sure you clean out the oil tank and clean out the sludge trap and you can't go wrong. Every !,000 or 2,000 miles depending on usage.

Please don't get into arguments about straight V multigrade oils. It's like having a course of leaches to cure your ailments instead of antibiotics.

Multigrades will seep through the oil pump faster than straight oils so wet sumping will occur sooner.

With roller big ends I use straight 40, with plain big ends I use multigrade. Seems to work - but that's only over the last 45 years or so.

I'm with you on this Gordon and top up with a bit of SAE 30 in cooler weather!

I cant understand why you say that SJ and higher quality oils are unsuitable for air cooled engines. Each step in the evolution of oil specifications requires higher performance in terms of piston cleanliness, resistance to oxidation, protection against wear, comparability with seal materials etc.

So they should be better for air cooled engines. Some advise against their use in the mistaken assumption that they give problems due to friction modifiers used in energy conserving oils. There is no point in using these in 15W40, 15W50, 20W50 oils as they could never meet the targets and the additives needed are expensive.

Previously charles_bovington wrote:

I cant understand why you say that SJ and higher quality oils are unsuitable for air cooled engines. Each step in the evolution of oil specifications requires higher performance in terms of piston cleanliness, resistance to oxidation, protection against wear, comparability with seal materials etc.

So they should be better for air cooled engines. Some advise against their use in the mistaken assumption that they give problems due to friction modifiers used in energy conserving oils. There is no point in using these in 15W40, 15W50, 20W50 oils as they could never meet the targets and the additives needed are expensive.

My understanding is that the later spec oils are formulated to provide cam protection to engines with lower stressed cam designs and do not have the additives needed for our outdated overstressed cams. I hear that the hot-rodders with tuned up old tech motors suffer cam problems with later spec oils and have switched back to SG specs. May be rubbish but I have had no lube problems with 40 mono, why change and risk irreplaceable parts?.

Previously robert_tuck wrote:

Previously charles_bovington wrote:

I cant understand why you say that SJ and higher quality oils are unsuitable for air cooled engines. Each step in the evolution of oil specifications requires higher performance in terms of piston cleanliness, resistance to oxidation, protection against wear, comparability with seal materials etc.

So they should be better for air cooled engines. Some advise against their use in the mistaken assumption that they give problems due to friction modifiers used in energy conserving oils. There is no point in using these in 15W40, 15W50, 20W50 oils as they could never meet the targets and the additives needed are expensive.

My understanding is that the later spec oils are formulated to provide cam protection to engines with lower stressed cam designs and do not have the additives needed for our outdated overstressed cams. I hear that the hot-rodders with tuned up old tech motors suffer cam problems with later spec oils and have switched back to SG specs. May be rubbish but I have had no lube problems with 40 mono, why change and risk irreplaceable parts?.

This is not the case,as someone who helped to formulate many of the oils marketed worldwide, I can assure you that our cams are not as highly stressed as those in the engines used in fired engine tests used in specifications, nor do our riding patterns reach the extreme conditions of these tests. Remember the classic oil market is quite lucrative and, to an extent, depends on convincing us that our engines have special needs.

OK Charles, So what should I buy?, my 99 is fairly std, No filter so low detergent, Wet sumps ( and always has) so 20 will wet sump twice as fast?, no oil seals on valves ,20 will get thro twice as quick ? ,ball race mains to chop up polymers?, big ends now 56 years old and a bit tired and loose, has 20 got the same film strength as 40?, plenty of old leak prone joints for thin oils to find. Low pressure head lube system flow calibrated to suit 40 by the makers ,head may flood?, I pay around £25 for 5 litres and the oil gets chucked at around 1500 miles. What would you buy?.

I too own a 99 but have completely refurbished the engine, so my situation is different from yours.

To deal with some of the points which you raised,

There is no virtue in using a low detergent oil, detergents are used to keep hot surfaces, pistons, clean and to keep rings free to move in their grooves. They do this by dissolving the deposits formed due to poor oxidation control.

Classic oils have worse oxidation control than do ' modern' counterparts.

Low detergency also goes with poor dispersancy.

Dispersants stop sludge particles and soot particles from agglomerating into chunks which block oil ways and erode the anti wear films formed by the anti wear agents.

So dispersants are good.

Polymers used in multigrades are not chopped up by roller mains. One of the standard oil approval tests involves high speed and high load shearing in a tapered roller bearing for a long period of time. The oil must stay within the viscosity limits of its grade to pass. There are also other high temperature high shear stress tests required. As with any approval test the limits are set by the engine manufactures and are backed by field trial data in a variety of vehicles.

The other problem which I have with the classic oil suppliers is that the specifications quoted are obsolete and so the oil sold cannot have been tested using the test methods which were appropriate all those years ago. You have to take their word for the fact that if it were possible to test them , they would have passed.

Over oiling of the low pressure rocker system with multigrades is not a problem, oil will get there quicker after start up and drain back easier. It will also get to cams and followers quicker, which is a good thing.

You have a well worn and loved engine, stay with what you have until you rebuild it, then go modern.

"You have a well worn and loved engine, stay with what you have until you rebuild it, then go modern." So right Charles. When I a mere 16 year old, my local bike shop stopped stocking Castrol GP 50 which I used in my Crusader Sports.Next oil change I put in GTX 20W-50 and wasrewarded by a nasty knocking noise 10 miles later - my first and only big end failure.

Previously Gordon Johnston wrote:

"You have a well worn and loved engine, stay with what you have until you rebuild it, then go modern." So right Charles. When I a mere 16 year old, my local bike shop stopped stocking Castrol GP 50 which I used in my Crusader Sports.Next oil change I put in GTX 20W-50 and wasrewarded by a nasty knocking noise 10 miles later - my first and only big end failure.

This would seem to be an atypical and unfortunate incident. I would point out that ASAP Norton specified multigrade oils.

The big difference in the oil requirements for the twins and the singles is that the twins have plain bearing rods whereas the singles have a roller bearing big end.

So, what does that mean.....

The twins are happyist with a multigrade oil so that in the cold weather the oil can get to the rods a little easier. With a single, the oil will get to the big end no matter what.

This all depends on the weather in your locale. In sunny California and in Northern OZ you can probably run the same oil all year. In Northern Europe, The UK, and Canada you might be better off with a multi-grade oil in the winter, especially on a twin.

Mike