Oil - It might not be what you think!!

[moleamol]

opieoilman said:

moleamol said: Any chance you could recommend an oil for a 1971 Capri 3000GT? It's a 3 litre V6 essex. Cheers. Sorry old bean, did not mean to ignore you, I have passed this one on to my friend Alan Walker Technical Head of Silkolen/Fuchs, he is the be all and end all on oil for pre 80's engines, what kind of mileage has it done as this will help. Cheers Guy.

It has a genuine 74,000 on the car but the engine looks fresh as a daisy and runs very well. Don't know if they are just good or if it has been rebuilt though.

I agree now, opieoilman is great

[opieoilman]

Pigeon said:

opieoilman said: Pigeon said: Opieoilman: what's your take on two-stroke oil for premix applications? Pigeon, How do you mean? there are a few choices for premix available, are you talking special pre mix oils or regular two stroke oil being used for premix? Cheers Guy. Well, the stuff they sell in petrol stations generally says it's equally suitable for premix or oil injection, which may or may not be true, or may just mean that it's equally crap for both I'm interested in your description of the chemistry behind different types of oil and how it affects their properties, and your insight into how what it says on the can relates to what the oil really is. I'm assuming that both chemistry and perhaps to a lesser extent inaccurate labelling are different in the realm of two-stroke oils with their different requirements - forming a good film from a carburetted mist, clean burning, low carbon deposits, but long term stability essentially irrelevant, no doubt you can add many more - and would appreciate a general summary of the situation with regard to the two-stroke oils available in petrol stations, bike shops and Half-rods, not racing types or stuff you have to get from specialists. I would also like to know your views on good "common" oil for an MZ TS250 - 250cc single, needle big and little ends, ball bearing mains, 20bhp, 6000rpm, premix, ridden using the power It is only a lowly bike but that is no reason not to use good oil! Thanks!

Pigeon,

I have had a reply from the Silkolene r and d chemist who designs the oils, here is what he said.

Guy
Two-stroke engines are mainly ‘boundary’ lubricated; ie they depend on thin oil films. So they respond to an oil with a high film strength. On the other hand, seeing that they burn their oil, the oil must burn off to leave few deposits. These can foul spark plugs, promote pre-ignition and even partially block exhaust ports. So 4-stroke oils, with high levels of calcium and zinc-based additives which burn off to leave zinc and calcium oxide deposits are no good.
For very high revving engines, esters and castor oil provide excellent film strength, and the ester types also run clean. Pro-2 is an ester race/motocross oil.
For good film strength with low smoke, a low ash oil based on esters and the smoke-reducing polymer PIB (poly isobutene) is a good choice, (JASO FC and ISO-L-EGD are low-smoke specs), such as Comp-2Plus. This would be ideal for a hard-working MZ TS 250. It is suitable for tank mix or injection. A lower-cost alternative is Comp-2 Injector.
All injector oils are OK for tank mix, but all tank mix oils are not necessarily OK for injection, because some are too thick to go through the pump and the feed pipes in cold weather. This is the only reason.

Au revoir, JR

Hope this helps mate.

Cheers

Guy.

[Pigeon]

Brilliant, many thanks. Not only are my questions answered but you've given me some useful background and an insight into why Castrol R is such a legend. Nice one.