Hi and happy holidays,

Is there any sense in using a higher grade oil then in bike specs (sj,sh if i recall correctly)?

Or perhaps it can actualy cause more harm then good?

There is an availability issue with thes "lower" grades for older vehicles and a technical issue of fitness to tasks?

much obliged,
Roy

Hi Roy,
This is an issue which ignites almost the same passion as religious argument between fervent adherents of opposing faiths. I started my working career as a lab technician in Castrol a very fine company which made very good lubricants and had many very clever chemists and lubrication scientists working for them. In a nutshell the options are to use a conventional oil often referred to as dino oil (some people with the bizarre belief it is made of dead dinosaurs!) and the adherents of synthetic oils. Now apart from diesel engine oils and oils made for spark ignition there is one further subdivision, that is between oils designed for motorcycles and those designed for passenger cars. There is some slight justification for this as the oils designed for latest generation cars have additives to reduce friction which is a good thing. However in other models of motorcycles lunatic designers with no care for engine longevity have designed in a so called wet clutch which means the clutch, a mixture of adhesives and ABRASIVE PARTICLES (yes I am shouting) is put inside the engine so as to be able to shed the detritus of clutch wear around inside the engine to grind away engine bearing metal before being hopefully captured by the oil filter. Fortunately the K-Bike designers eschewed such a mechanical abortion and we have a separate air cooled clutch as do cars with manual gearboxes, so the issue of of friction modifiers being bad for the clutch does not exist in a K-Bike of our vintage. The one thing that may be a concern is that latest passenger car oils in some cases have reduced levels of zinc as an additive because of the risk of poisoning by zinc of the catalytic converter in modern vehicles. Appropriate levels of zinc are beneficial in minimising wear.

So in general what should you do. The first question I would ask is what is your predominant journey distance? one person I was discussing with a while back their wife never went more than 2 miles in the morning and 2 miles back home in the evening in a big passenger car which would really count as severe service calling for double the normal frequency of oil and filter changes plus an oil with exceptional cold sludge dispersant capabilities. If you do reasonable distances 20 miles or so and are prepared to change oil and filter at the normal recommended frequency then almost any premium lubricating oil of the correct viscosity will be fine. If you are aiming to get extended drain intervals then you should consider going to a genuine synthetic such as Redline or Amsoil but they are expensive. My gut feel is for you a premium oil with regular changes will be perfect for you esoecially as engine milages of 200,000 are not unknown for K-Bikes.
There is no way you can damage your engine by using a better oil nor by changing it too frequently, you can however do the reverse by using inferior oil and changing it infrequently or even never as a person I knew once. Several interesting oil articles exist on the web some are written by amsoil distributors which I hasten to say does not make them untrue quite the opposite those I have seen are factual and interesting presenting a compelling argument for the use of their product in the more extreme service conditions which ordinary oils do badly in. I recommend you peruse http://www.ibmwr.org/otech/oilreport.html

Bottom line avoid regular short journeys where the bike does not warm up, buy good oil, buy genuine filters and change both of them regularly and you will be doing the best you can to keep your engine in good condition.
Regards,
K-BIKE