Which weight do you use for racing? What's the benefit of 15-50 over 10-40 for a track bike?
It specifically has to do with the plane bearing clearances in your bike and what they're meant to hold... it isn't THAT important unless you've built a motor with something in mind. On a stock bottom end I run redline 30W racing oil, but if you ask 1 million people you'll likely get 1 million answers.
I agree this topic is very controversial
If your motors loose use heavy oil .
If your not over heating your oil it will be just fine.
Rottela is very affordable and has not caused me any concern
I've had people ask this question before and I reply does it say anything on the filler cap?
Something to keep in mind is that the manufacturer recommended viscosity frequently is related to the sizing of the various passages and restictors in the oil system and choosing a different oil can cause starvation or excess oil in different areas of the engine. Of course this is for the stock engine, once it has been modified all bets are off.
Quote from: Hawk on April 28, 2008, 07:45:40 AM
Something to keep in mind is that the manufacturer recommended viscosity frequently is related to the sizing of the various passages and restictors in the oil system and choosing a different oil can cause starvation or excess oil in different areas of the engine. Of course this is for the stock engine, once it has been modified all bets are off.
+1, mfr recommendation is key IF internals are stock. If not, then whoever built your motor should hopefully be able to give you detailed info an which weight oil to use in which conditions.
In the case where mfr recommendations overlap for different operating conditions, such as ambient temperature, be sure to balance viscosity requirements against the other side effects, such as additional heat generated, etc. Also keep in mind that mfr recommendations are intended to be good for 3k miles or something like that, and you likely change it every weekend, so factor in the effect of usage period when choosing from a range of options presented by the mfr.
You would be well served to read something like the Engine Oil Bible to get the basic facts on engine oil, because as someone pointed out above there is a lot of rumour and half-assed facts thrown around the pits regarding lots of racing tech, but especially lubricants.
http://www.carbibles.com/engineoil_bible.html