timppl Posted December 10, 2012 Share Posted December 10, 2012 My Series 3 takes EP90. I have been using EP80W/90 but I was wondering about the effect of using EP70W/80. Obviously this is less viscous than the EP90, but are they othewise equivalent ie with the EP additives and general lubricating capability? It would be useful if EP70W80 can be used, especially in this winter weather. Regards Tim Quote Link to comment Share on other sites More sharing options...
Phil Hancock Posted December 10, 2012 Share Posted December 10, 2012 You want a GL4 spec oil so if the 70/80 is a higher spec i would check with the manufacturers tech department to ask if it is safe with yellow metals. Quote Link to comment Share on other sites More sharing options...
disco2hse Posted December 11, 2012 Share Posted December 11, 2012 Be very careful with the selection of oil you make. I have found that companies frequently change the formulations in oils. Be equally wary of anyone who says I have been using X for 20 years without any problems (of course you later learn they have gone through four gearboxes in the same time) because in that time the oil they started buying is not the same stuff for sale now, even though it may have the same brand name. The main issue is that newer machines tend not to have bronze bearings, etc. and those yellow metals are more porous than other alloys often used in machines nowadays. Thus, the oils that are formulated for use in newer machines are designed for the new alloys that are used. The problem is that the chemicals that are used for those alloys in newer machines are formed of long chains and when cool they are absorbed by the yellow porous metals, then when subjected to heat, the molecules expand and fracture yellow metals. This causes those metals to corrode quickly. You will know when you have used the wrong oil because when you drain the gearbox you will see traces of copper in the sediment. Typically, the damage occurs when the oil exceeds 70ºC, so if you never get to that temperature, then you will not be likely to have any problems. If you exceed that temperature, you probably will. A brand of oil I have found locally is Shell Spirax S4 TXM 80W. This is a GL4 oil and is formulated for use in tractor transmissions and marine applications, so it comes in 20-60 litre containers. Quote Link to comment Share on other sites More sharing options...
timppl Posted December 11, 2012 Author Share Posted December 11, 2012 Thanks guys, lots of very useful info there Regards Tim Quote Link to comment Share on other sites More sharing options...
secondjeremy Posted December 12, 2012 Share Posted December 12, 2012 I use Comma 80/90 in my vehicles as its a GL4 oil and won't attack the yellow metals (and I have a convenient supplier) To my surprise the gearchange on my S3 with a sound gearbox has not become obstructive in cold weather as I was expecting it to do. So perhaps there are advantages to the multigrade spec. Quote Link to comment Share on other sites More sharing options...
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