pollux 1 Posted May 1, 2011 Share Posted May 1, 2011 when i start flying with a brand new plane how can you whitch oil is in the motor right now? (sae20,40) or if i want to refill... sae40 use in normal temp, and sae20 mostly in extreme cold? what is the temp margins? Link to comment Share on other sites More sharing options...
Snave 466 Posted May 1, 2011 Share Posted May 1, 2011 What you need is HERE 1 Link to comment Share on other sites More sharing options...
pollux 1 Posted May 1, 2011 Author Share Posted May 1, 2011 thank you! Link to comment Share on other sites More sharing options...
Ron Attwood 33 Posted May 1, 2011 Share Posted May 1, 2011 I saw the subject and thought "Oops, there goes the neighbourhood!" Must do something about my thought processes. Lots of foreigners scratching their heads. Link to comment Share on other sites More sharing options...
Snave 466 Posted May 1, 2011 Share Posted May 1, 2011 What you do in your own cockpit is your own concern... Link to comment Share on other sites More sharing options...
alehead 126 Posted May 2, 2011 Share Posted May 2, 2011 Given the Rotax official document I find it interesting that Marcel used only single grade oils here, although it would appear that multigrade oils are the norm... Armed with the correct information, not that it makes a lot of difference, as long as you use the right oil for the job... Andrew Link to comment Share on other sites More sharing options...
bliksimpie 14 Posted May 2, 2011 Share Posted May 2, 2011 What you need is HERE So for the less technically inclined. Which single grade oil compare to which multigrade SAE20 = ? SAE40 = ? is SAE40 = SAE 5W 40 or SAE 20W 40 Link to comment Share on other sites More sharing options...
alehead 126 Posted May 2, 2011 Share Posted May 2, 2011 Based on what I have read, there is no direct comparison as such. SAE 40 is only equivalent to SAE 5W 40 at high temperature, as indicated below, because the low temperature capabilities of SAE 5W 40 are SAE 5 at low temperature. SAE 20W 40 is equivalent to SAE 20 at low temp. and SAE 40 at high temp. Confusing perhaps... The multigrade oils are labelled as having a specific viscosity at low temperature and a different one at high temperature. The viscosity followed by the W indicates the 0°F viscosity for the oil, the second figure is the viscosity at 210°F. If the OAT is lower, you want to use SAE 20. If your OAT is higher, you should consider using SAE 40, follow the guideline for the 20W40 multigrade and keep to SAE 20 at lower temps, SAE 40 at higher... For wont of a better explanation, I hope this helps... Andrew Link to comment Share on other sites More sharing options...
Snave 466 Posted May 2, 2011 Share Posted May 2, 2011 Exactly, as there is no direct comparison between multi-grade auto oil and the typical single grade aero-engine oils. In its design and construction the Rotax owes more to modern motorcycle engines than it does to aviation, hence the specific advice to use modern motorcycle oils, which are ALWAYS multi-grade. However, if you look into these in more detail (I used to be involved in R & D development of lubricants for manufacturers) you will discover that even with similar packaging, oils for different auto markets can have differing characteristics. Not so with airplane oils. So Andrew (and Marcel) is right, keep it simple: If its cold use SAE20. If hot use SAE40. ...and use the chart to decide when `cold` becomes `hot`, mindful of the fact that you need to consider not just the OAT at ground level, but also the OAT at wherever you plan on spending a goodly proportion of the flight! So for pattern work you'd make your choice based on ground level OAT (as the majority of the high-power flight time is going to be in the `low, slow` regime as you climb to circuit height, whereas if you're going touring you'd want to consider the temps at your cruise altitude where you plan to spend the next 2-3 hours at reduced power settings. The impact of not having the correct oil is usually in accelerated engine wear (particularly from cold) a reduction in performance due to increased friction, and oil and engine temperatures that vary from the norm and so also affect performance and handling. And it makes no difference whether you use a `hot` oil in a `cold` environment or a `cold` oil in a `hot` environment, the failure rate and accelerated wear is exactly the same. Either is just as bad for the engine! The common recommended oil change interval for Rotax 912's is 25 hours. The manufacturer stated requirement is 60. The latter reflects the correct choice of lube, used in the right way and chosen for the environment - a manufacturers `proper` use idyll. The former represents the rather more random reality of an aircraft which may be in constant use at high power settings as a trainer, or see only weekend and occasional use as a light tourer around long periods of inactivity, where longevity and care and consideration have a higher priority. Link to comment Share on other sites More sharing options...
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