Author - David Angel F2 Motorcycles

I have read the recent article about mono grade oils in the club publication 'Horizontal News' and would like to make the following comments. As anyone who has visited us, or bought a bike from us will know, I use and strongly recommend the use of Fully Synthetic Oils. Whilst it is true that mono grades are shear stable I feel that they simply do not have a wide enough temperature range, to fully protect your engine under typical all year round riding conditions. So surely if a shear stable oil could be found that gave the same or better protection over a wider temperature range this would be better.

I have contacted various oil companies and asked them to recommend an oil based on our engine but without telling them the make. I think if you tell them the make they just look it up in an out of date list probably compiled before fully synthetics were widely available. I asked them to recommend an oil that would be shear stable in a roller bearing engine but could be used over a wide temperature range. I also said if there really is no oil with shear stability to match mono grades they should tell me so I could correct my current recommendations. I told them the engine size, type, bearing type, pump type, max power, max revs. A summery of their replies follows:

ROCK OIL

With roller bearing cranks, you need an oil made with large molecule bases. One needs to be careful not to go too thick as it then prevents rapid circulation at cold start - which is when 70% of engine wear takes place.

Viscosity index improves; the polymers that make a base material into a multigrade vary enormously in their shear stability. We at Rock use an Isoprene Diene type, the most shear stable. Synthetics offer a demonstrable benefit in all areas of lubrication compared with mineral oils. They have a higher natural VI and are more shear stable.

I would definitely recommend Rock Oil Synthesis 4 Racing. A 15w50 fully synthetic oil with API SL, ACEA A3, and JASO Ma specifications. We also have an interesting 20w6O racing oil called TRM which I would recommend for any older engines. We use TRM for endurance racing in roller bearing cranked bikes, with phenomenal results.

Drain intervals are always tricky. As an oil Company, we are always advised to follow the manufacturers recommendation. There are many factors that influence drain intervals. Older type engines tend to produce more or dirtier by-products from the combustion process. However, for a good synthetic oil, your 2500 km seems too short. I would feel confident at double that.

BP

Based on the info provided we would suggest our Formula RS 10w60. This is a fully synthetic oil using highly shear stable VI improvers. It is only the VII's that are prone to shearing permanently. (Castrol) Formula RS is our flagship brand and uses VI.

MORRIS OILS

20W/50 grades tend to be formulated with mineral oils that provide a good oil film, ideal for roller bearings. They exhibit minimal shear thinning. 20W grades will also provide good cold starting down to -15 degrees C, so only really cold weather may be a problem.

In conclusion I would recommend the following product from our range: Morris V-Twin 20W/50. Do not be put off by the name; this oil is suitable for motorcycle engines that are not a V-Twin configuration. 20W/50 engine oils, like V-Twin 20W/50, tend to be mineral oil based.   Mineral oils, having thicker oil films, are much better at lubricating roller bearing cranks. There would be no advantage to using a fully synthetic product in this application.

MOBIL

Following comments from Mobil's Technical Manager, our recommendation for the bikes you are stocking are as follows: Engine - Mobil 1 Racing 4T 15w50 fully Synthetic)

F2 COMMENTS

As you can see with the exception of Morris Oils, all who bothered to answer have recommended the use of Fully Synthetic oils. I am still waiting for answers from another 2 or 3 companies and if they ever bother I will pass this information on.

I will continue to use and recommend the use of good quality fully synthetic oils using the highly shear stable VI improvers. I will be working with Castrol this year to give advice on oil change mileage using Castrol Formula RS. I will put it in my bike and then take small samples to send to their laboratory at 1000 KM intervals, they will then test it for sheared molecules and let me have the results.

2009 Castrol testing update, both mineral and synthetic oils were sampled and tested by Castrol over several thousand km’s. Briefly these tests showed that the synthetic oil had not sheared and contained virtually no contamination of metals from bearings suggesting that the engine was adequately protected. The mineral oil showed considerable reduction in film strength as well as containing contamination from various metals, presumably from the bearing or sliding surfaces of the engine.

I cannot recommend extending the oil change interval as standard practice even with these test results. Even the best oil in the world will still contain the acid by products of combustion and with get dirty. We have many customers who have extended the oil change interval using synthetic oils when it has been unavoidable during long distance trips. These bikes have suffered no apparent damage, but this is occasional rather than routine extension of oil change periods.

Notes on Semi-Synthetics by David Angel. (December 2009)

Since this article was first written and the original testing carried out there has been big improvements in semi-synthetic oils. Take a look at the API letters. They will say something like SF, SJ, etc up to SM. As a rule the higher the second letter the better quality the oil. There are a few semi-synthetics on the market now meet API SM standards. These oils are not as good as the best synthetic oils, but they are considerably better than mineral oils whilst offering a cost saving over the best synthetics. API in itself is not a measurement of shear stability, but manufacturers aiming at passing the SM standard will have to be using high quality viscosity index improvers and additive packs.

Our current recommendations for Urals are.

Urals built before 2007 or having the Russian gearbox internals.

Engine: 15w50, 20w50 semi-synthetic meeting API SM or higher.

Any of the fully synthetics mentions earlier.

Gearbox: EP80, EP90,

Final drive: EP 80w140, EP85w140

Urals built from 2007 or having German gearbox internals
 

Engine and gearbox: 15w50, 20w50 semi-synthetic meeting API SM or higher.

Any of the fully synthetics mentions earlier.