Oils for aircooled high revving bike engine

Hey lubedude or oildoc, is there any way of telling whether or not an oil is designed to take the higher temperatures that an aircooled high-revving engine produces?<br /> I'm trying to find something that I can put in my girlfriend's street legal aircooled ex-dragbike. <br />At the moment it's using the generic castrol 10/40 motorcycle oil but we're noticing that the gearshift becomes noticeably notchier after 1000 miles and changing the oil at that point.The gearbox is absolutely perfect, no noticeable wear on selectors or gears.<br />I'm going to be fitting an oilcooler to it soon anyway but even then the oil will be taking a real hammering in comparison with a liquid cooled low-revving car engine.<br />It hits 11000 rpm on a regular basis and with the kind of internal tolerances required to run as hot as it does there's quite a bit of blow-past from the combustion process when cold.<br />Also, what's your opinion on Slick 50 and other one-time teflon oil additives? The engine is a 'unit' construction so the engine shares its oil with the gearbox and the oil-bathed clutch.<br />This means any additives that go in the oil at every change are a no-no as they make the clutch slip like mad-even with the heavy duty clutch and springs in there.If I use a one-time teflon additive I'll put an old clutch in for the duration of the treatment.

Re: Oils for aircooled high revving bike engine

Originally posted by Nos4r2:<br />Also, what's your opinion on Slick 50 and other one-time teflon oil additives?

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ABSOLUTLY NOT UNDER "ANY" CERCUMSTANCES USE ANYTHING LIKE THAT IN YOUR BIKE!!! <br /><br />There have been many test by major Bike magazines that say the synthetic car oils are just as good as the bike oils and sometimes better. Of course I would recomend the Amsoil Motorcycle oil, but Mobil 1 will be fine also. You will notice better shifting when hot with either of these oils. Follow the weight requirements of the Bike manufacture.

Re: Oils for aircooled high revving bike engine

hahaha well that's a nice positive no! Thanks!<br /><br />Just to clarify, this isn't a standard bike engine at all-It's running nice lumpy cams and a 10.9:1 compression ratio, but it's VERY old (1978)therefore runs considerably hotter than modern aircooled engines.<br />I can't actually find the weight thats specified by the manufacturer in the UK anymore<br />They recommend 20/50(it's a full rollerbearing engine) and the only 20/50 that seems to be available here is the appalling recycled (read filtered re-used contaminated cr@p from oilbanks) that doesnt even feel like oil anymore-api rating SC.Is Amsoil available in the UK? Never seen it here.

Re: Oils for aircooled high revving bike engine

Nos4r2, you might want to read this info. I'm sure it is put out by the manufacturer, who would have a proprietary interest but facts are facts <br /><br /> http://www.synthetic-motor-oil.us/they_say_nothing_outperforms_mobil_1.htm <br /><br />read this as well;<br /><br /> http://www.acehioil.com/history.htm <br /><br />I would do an internet search for Amsoil in the UK or you could email Amsoil and ask them re availability.

Re: Oils for aircooled high revving bike engine

Thanks Boomyal, I couldnt have said it better.

Re: Oils for aircooled high revving bike engine

is there any way of telling whether or not an oil is designed to take the higher temperatures that an aircooled high-revving engine produces?

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Look for oils with high phosphorus and zinc content. <br /><br />Air-cooled bikes won't have the emissions equipment like automobiles, which can damaged by the higher levels of some of these components.<br /><br />

Also, what's your opinion on Slick 50 and other one-time teflon oil additives? The engine is a 'unit' construction so the engine shares its oil with the gearbox and the oil-bathed clutch.

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With a common sump, you do not want to use an oil that contains friction modifiers like teflon.<br /><br />I don't like to solicit oil brands, but you should check out Mobil's MX4T and V-Twin 20W-50. They also make a Racing 2T oil. All these oils are specifically designed exactly for your situation.